CenterPoint Energy (CNP) 10-Q 3 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	6 Months Ended
	Jun. 30, 2018	Jul. 23, 2018	Jun. 30, 2017
Entity Information [Line Items]
Entity Registrant Name	CENTERPOINT ENERGY INC.
Entity Central Index Key	1,130,310
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		431,553,691
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 11,722,467,012
Houston Electric [Member]
Entity Information [Line Items]
Entity Registrant Name	CENTERPOINT ENERGY HOUSTON ELECTRIC LLC
Entity Central Index Key	48,732
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
CERC Corp [Member]
Entity Information [Line Items]
Entity Registrant Name	CENTERPOINT ENERGY RESOURCES CORP
Entity Central Index Key	1,042,773
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,000
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes

CONDENSED STATEMENTS OF CONSOLI

CONDENSED STATEMENTS OF CONSOLIDATED INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Utility revenues	$ 1,341	$ 1,222	$ 3,235	$ 2,768
Non-utility revenues	845	921	2,106	2,110
Total	2,186	2,143	5,341	4,878
Expenses:
Utility natural gas	188	150	825	600
Non-utility natural gas	790	882	2,063	2,011
Operation and maintenance	578	518	1,147	1,061
Depreciation and amortization	342	254	656	480
Taxes other than income taxes	101	99	212	195
Total	1,999	1,903	4,903	4,347
Operating Income	187	240	438	531
Other Income (Expense):
Gain on marketable securities	22	23	23	67
Loss on indexed debt securities	(254)	(13)	(272)	(23)
Interest and other finance charges	(91)	(77)	(169)	(155)
Interest on Securitization Bonds	(14)	(20)	(30)	(40)
Equity in earnings of unconsolidated affiliate, net	58	59	127	131
Other, net	4	(1)	7	(1)
Total	(275)	(29)	(314)	(21)
Income (Loss) Before Income Taxes	(88)	211	124	510
Income tax expense (benefit)	(13)	76	34	183
Net Income (Loss)	$ (75)	$ 135	$ 90	$ 327
Basic Earnings (Loss) Per Share	$ (0.17)	$ 0.31	$ 0.21	$ 0.76
Diluted Earnings (Loss) Per Share	(0.17)	0.31	0.21	0.75
Dividends Declared Per Share	$ 0.2775	$ 0.2675	$ 0.2775	$ 0.5350
Weighted Average Shares Outstanding, Basic	431,523,000	430,996,000	431,378,000	430,896,000
Weighted Average Shares Outstanding, Diluted	431,523,000	433,797,000	434,407,000	433,697,000
Houston Electric [Member]
Revenues:
Total	$ 854	$ 752	$ 1,609	$ 1,390
Expenses:
Operation and maintenance	351	343	693	684
Depreciation and amortization	262	180	495	332
Taxes other than income taxes	60	58	121	118
Total	673	581	1,309	1,134
Operating Income	181	171	300	256
Other Income (Expense):
Interest and other finance charges	(36)	(32)	(69)	(65)
Interest on Securitization Bonds	(14)	(20)	(30)	(40)
Other, net	(3)	(2)	(6)	(6)
Total	(53)	(54)	(105)	(111)
Income (Loss) Before Income Taxes	128	117	195	145
Income tax expense (benefit)	27	42	42	52
Net Income (Loss)	101	75	153	93
CERC Corp [Member]
Revenues:
Utility revenues	487	470	1,630	1,377
Non-utility revenues	841	917	2,098	2,103
Total	1,328	1,387	3,728	3,480
Expenses:
Utility natural gas	188	150	825	600
Non-utility natural gas	790	882	2,063	2,011
Operation and maintenance	217	190	455	405
Depreciation and amortization	72	68	145	134
Taxes other than income taxes	39	38	87	72
Total	1,306	1,328	3,575	3,222
Operating Income	22	59	153	258
Other Income (Expense):
Interest and other finance charges	(33)	(31)	(62)	(60)
Equity in earnings of unconsolidated affiliate, net	58	59	127	131
Other, net	(1)	(4)	(5)	(9)
Total	24	24	60	62
Income (Loss) Before Income Taxes	46	83	213	320
Income tax expense (benefit)	10	29	47	119
Net Income (Loss)	$ 36	$ 54	$ 166	$ 201

CONDENSED STATEMENTS OF CONSOL3

CONDENSED STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net income (loss)	$ (75)	$ 135	$ 90	$ 327
Other comprehensive income:
Adjustment to pension and other postretirement plans (net of tax of $-0-, $1, $1 and $2)	2	1	3	2
Net deferred gain (loss) from cash flow hedges (net of tax of $-0-, $-0-, $1 and $-0-)	(1)	0	3	(1)
Total	1	1	6	1
Comprehensive income (loss)	(74)	136	96	328
Houston Electric [Member]
Net income (loss)	101	75	153	93
Other comprehensive income:
Net deferred gain (loss) from cash flow hedges (net of tax of $-0-, $-0-, $1 and $-0-)	0	0	4	(1)
Total	0	0	4	(1)
Comprehensive income (loss)	101	75	157	92
CERC Corp [Member]
Net income (loss)	36	54	166	201
Other comprehensive income:
Comprehensive income (loss)	$ 36	$ 54	$ 166	$ 201

CONDENSED STATEMENTS OF CONSOL4

CONDENSED STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME (Parentheticals) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Tax benefit (expense) on adjustment related to pension and postretirement plans	$ 0	$ (1)	$ (1)	$ (2)
Tax expense (benefit) on net deferred gain (loss) from cash flow hedges	0	0	1	0
Houston Electric [Member]
Tax expense (benefit) on net deferred gain (loss) from cash flow hedges	$ 0	$ 0	$ 1	$ 0

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 328	$ 260
Investment in marketable securities	584	960
Accounts receivable, less bad debt reserve	958	1,000
Accrued unbilled revenues	207	427
Natural gas inventory	152	222
Materials and supplies	192	175
Non-trading derivative assets	74	110
Taxes receivable	39	0
Prepaid expenses and other current assets	167	241
Total current assets	2,701	3,395
Property, Plant and Equipment:
Property, plant and equipment	19,585	19,031
Less: accumulated depreciation and amortization	6,188	5,974
Property, plant and equipment, net	13,397	13,057
Other Assets:
Goodwill	867	867
Regulatory assets	2,067	2,347
Non-trading derivative assets	46	44
Investment in unconsolidated affiliate	2,451	2,472
Preferred units – unconsolidated affiliate	363	363
Other	216	191
Total other assets	6,010	6,284
Total Assets	22,108	22,736
Current Liabilities:
Short-term borrowings	0	39
Current portion of VIE Securitization Bonds long-term debt	446	434
Indexed debt, net	26	122
Current portion of other long-term debt	50	50
Indexed debt securities derivative	641	668
Accounts payable	706	963
Taxes accrued	103	181
Interest accrued	118	104
Dividends accrued	0	120
Non-trading derivative liabilities	26	20
Due to ZENS note holders	382	0
Other	344	368
Total current liabilities	2,842	3,069
Other Liabilities:
Deferred income taxes, net	3,168	3,174
Non-trading derivative liabilities	12	4
Benefit obligations	723	785
Regulatory liabilities	2,521	2,464
Other	412	357
Total other liabilities	6,836	6,784
Long-term Debt:
VIE Securitization Bonds, net	1,193	1,434
Other long-term debt, net	6,567	6,761
Total long-term debt, net	7,760	8,195
Commitments and Contingencies (Note 14)
Shareholders’ Equity:
Cumulative preferred stock, $0.01 par value, 20,000,000 shares authorized, none issued or outstanding	0	0
Common stock	4	4
Additional paid-in capital	4,215	4,209
Retained earnings	513	543
Accumulated other comprehensive income (loss)	(62)	(68)
Total shareholders’ equity	4,670	4,688
Total Liabilities and Shareholders’ Equity	22,108	22,736
Houston Electric [Member]
Current Assets:
Cash and cash equivalents	253	238
Accounts and notes receivable	389	284
Accounts and notes receivable–affiliated companies	32	7
Accrued unbilled revenues	122	120
Materials and supplies	125	119
Taxes receivable	23	0
Prepaid expenses and other current assets	59	62
Total current assets	1,003	830
Property, Plant and Equipment:
Property, plant and equipment	11,812	11,496
Less: accumulated depreciation and amortization	3,741	3,633
Property, plant and equipment, net	8,071	7,863
Other Assets:
Regulatory assets	1,321	1,570
Other	35	29
Total other assets	1,356	1,599
Total Assets	10,430	10,292
Current Liabilities:
Current portion of VIE Securitization Bonds long-term debt	446	434
Accounts payable	208	243
Accounts and notes payable–affiliated companies	121	104
Taxes accrued	61	116
Interest accrued	75	65
Other	93	120
Total current liabilities	1,004	1,082
Other Liabilities:
Deferred income taxes, net	1,025	1,059
Benefit obligations	143	146
Regulatory liabilities	1,265	1,263
Other	56	54
Total other liabilities	2,489	2,522
Long-term Debt:
VIE Securitization Bonds, net	1,193	1,434
Other long-term debt, net	3,280	2,885
Total long-term debt, net	4,473	4,319
Commitments and Contingencies (Note 14)
Shareholders’ Equity:
Common stock	0	0
Additional paid-in capital	1,697	1,696
Retained earnings	763	673
Accumulated other comprehensive income (loss)	4	0
Total shareholders’ equity	2,464	2,369
Total Liabilities and Shareholders’ Equity	10,430	10,292
CERC Corp [Member]
Current Assets:
Cash and cash equivalents	1	12
Accounts receivable, less bad debt reserve	566	713
Accounts and notes receivable–affiliated companies	15	6
Accrued unbilled revenues	85	307
Natural gas inventory	152	222
Materials and supplies	67	56
Non-trading derivative assets	74	110
Prepaid expenses and other current assets	80	166
Total current assets	1,040	1,592
Property, Plant and Equipment:
Property, plant and equipment	7,104	6,888
Less: accumulated depreciation and amortization	2,136	2,036
Property, plant and equipment, net	4,968	4,852
Other Assets:
Goodwill	867	867
Regulatory assets	173	181
Non-trading derivative assets	46	44
Investment in unconsolidated affiliate	2,451	2,472
Other	97	104
Total other assets	3,634	3,668
Total Assets	9,642	10,112
Current Liabilities:
Short-term borrowings	0	39
Accounts payable	434	669
Accounts and notes payable–affiliated companies	36	611
Taxes accrued	48	75
Interest accrued	38	32
Customer deposits	75	76
Non-trading derivative liabilities	26	20
Other	152	137
Total current liabilities	809	1,659
Other Liabilities:
Deferred income taxes, net	1,330	1,289
Non-trading derivative liabilities	12	4
Benefit obligations	98	97
Regulatory liabilities	1,256	1,201
Other	352	297
Total other liabilities	3,048	2,888
Long-term Debt:
Total long-term debt, net	2,722	2,457
Commitments and Contingencies (Note 14)
Shareholders’ Equity:
Common stock	0	0
Additional paid-in capital	2,528	2,528
Retained earnings	529	574
Accumulated other comprehensive income (loss)	6	6
Total shareholders’ equity	3,063	3,108
Total Liabilities and Shareholders’ Equity	$ 9,642	$ 10,112

CONDENSED CONSOLIDATED BALANCE6

CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Cash and cash equivalents	$ 328	$ 260
Accounts receivable, less bad debt reserve	958	1,000
Bad debt reserve	21	19
Prepaid expenses and other current assets	167	241
Regulatory assets	$ 2,067	$ 2,347
Cumulative preferred stock par value (in dollars per share)	$ 0.01	$ 0.01
Cumulative preferred stock authorized (in shares)	20,000,000	20,000,000
Cumulative preferred stock outstanding (in shares)	0	0
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	1,000,000,000	1,000,000,000
Common stock outstanding (in shares)	431,547,782	431,044,845
Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents	$ 253	$ 230
Accounts receivable, less bad debt reserve	112	73
Prepaid expenses and other current assets	37	35
Regulatory assets	1,293	1,590
Houston Electric [Member]
Cash and cash equivalents	253	238
Bad debt reserve	1	1
Prepaid expenses and other current assets	59	62
Regulatory assets	1,321	1,570
Houston Electric [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Cash and cash equivalents	253	230
Accounts receivable, less bad debt reserve	112	73
Prepaid expenses and other current assets	37	35
Regulatory assets	1,293	1,590
CERC Corp [Member]
Cash and cash equivalents	1	12
Accounts receivable, less bad debt reserve	566	713
Bad debt reserve	20	18
Prepaid expenses and other current assets	80	166
Regulatory assets	$ 173	$ 181

CONDENSED STATEMENTS OF CONSOL7

CONDENSED STATEMENTS OF CONSOLIDATED CASH FLOW (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows from Operating Activities:
Net income	$ 90	$ 327
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	656	480
Amortization of deferred financing costs	18	12
Deferred income taxes	(12)	95
Unrealized gain on marketable securities	(23)	(67)
Loss on indexed debt securities	272	23
Write-down of natural gas inventory	1	0
Equity in earnings of unconsolidated affiliate, net of distributions	(9)	(131)
Pension contributions	(64)	(18)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	232	234
Inventory	52	(20)
Taxes receivable	(39)	30
Accounts payable	(246)	(158)
Fuel cost recovery	69	(12)
Non-trading derivatives, net	64	(49)
Margin deposits, net	(9)	(43)
Interest and taxes accrued	(64)	(17)
Net regulatory assets and liabilities	57	(34)
Other current assets	(4)	10
Other current liabilities	(13)	(29)
Other assets	(3)	(1)
Other liabilities	60	27
Other, net	8	18
Net cash provided by operating activities	1,093	677
Cash Flows from Investing Activities:
Capital expenditures	(697)	(649)
Acquisitions, net of cash acquired	0	(132)
Distributions from unconsolidated affiliate in excess of cumulative earnings	30	149
Proceeds from sale of marketable securities	398	0
Other, net	2	(8)
Net cash used in investing activities	(267)	(640)
Cash Flows from Financing Activities:
Decrease in short-term borrowings, net	(39)	(11)
Proceeds from (payments of) commercial paper, net	(1,188)	284
Proceeds from long-term debt, net	997	298
Payments of long-term debt	(230)	(469)
Debt issuance costs	(35)	(6)
Payment of dividends on common stock	(240)	(230)
Distribution to ZENS note holders	(16)	0
Other, net	(5)	(4)
Net cash provided by (used in) financing activities	(756)	(138)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	70	(101)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	296	381
Cash, Cash Equivalents and Restricted Cash at End of Period	366	280
Cash and Cash Equivalents at Beginning of Period	260
Cash and Cash Equivalents at End of Period	328
Houston Electric [Member]
Cash Flows from Operating Activities:
Net income	153	93
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	495	332
Amortization of deferred financing costs	6	6
Deferred income taxes	(38)	23
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	(107)	(63)
Accounts receivable/payable–affiliated companies	78	(35)
Inventory	(6)	(1)
Taxes receivable	(23)	(38)
Accounts payable	(6)	57
Interest and taxes accrued	(45)	(41)
Net regulatory assets and liabilities	(59)	(59)
Other current assets	4	2
Other current liabilities	(11)	(7)
Other assets	2	4
Other liabilities	2	1
Other, net	(2)	5
Net cash provided by operating activities	443	279
Cash Flows from Investing Activities:
Capital expenditures	(441)	(414)
Decrease (increase) in notes receivable–affiliated companies	(26)	5
Other, net	(1)	(9)
Net cash used in investing activities	(468)	(418)
Cash Flows from Financing Activities:
Proceeds from long-term debt, net	398	298
Payments of long-term debt	(230)	(219)
Decrease in notes payable–affiliated companies	(60)	0
Dividend to parent	(63)	(42)
Debt issuance costs	(4)	(3)
Other, net	1	1
Net cash provided by (used in) financing activities	42	35
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	17	(104)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	274	381
Cash, Cash Equivalents and Restricted Cash at End of Period	291	277
Cash and Cash Equivalents at Beginning of Period	238
Cash and Cash Equivalents at End of Period	253
CERC Corp [Member]
Cash Flows from Operating Activities:
Net income	166	201
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	145	134
Amortization of deferred financing costs	4	4
Deferred income taxes	41	115
Write-down of natural gas inventory	1	0
Equity in earnings of unconsolidated affiliate, net of distributions	(9)	(131)
Changes in other assets and liabilities, excluding acquisitions:
Accounts receivable and unbilled revenues, net	339	295
Accounts receivable/payable–affiliated companies	(14)	(1)
Inventory	58	(18)
Accounts payable	(248)	(203)
Fuel cost recovery	69	(12)
Non-trading derivatives, net	61	(49)
Margin deposits, net	(9)	(43)
Interest and taxes accrued	(21)	(27)
Net regulatory assets and liabilities	92	(1)
Other current assets	7	12
Other current liabilities	8	(14)
Other assets	4	5
Other liabilities	52	10
Other, net	0	1
Net cash provided by operating activities	746	278
Cash Flows from Investing Activities:
Capital expenditures	(230)	(223)
Acquisitions, net of cash acquired	0	(132)
Distributions from unconsolidated affiliate in excess of cumulative earnings	30	149
Other, net	3	1
Net cash used in investing activities	(197)	(205)
Cash Flows from Financing Activities:
Decrease in short-term borrowings, net	(39)	(11)
Proceeds from (payments of) commercial paper, net	(333)	149
Proceeds from long-term debt, net	599	0
Decrease in notes payable–affiliated companies	(570)	0
Dividend to parent	(211)	(248)
Debt issuance costs	(5)	(1)
Contribution from parent	0	38
Other, net	(1)	0
Net cash provided by (used in) financing activities	(560)	(73)
Net Decrease in Cash and Cash Equivalents	(11)	0
Cash and Cash Equivalents at Beginning of Period	12	1
Cash and Cash Equivalents at End of Period	$ 1	$ 1

Background and Basis of Present

Background and Basis of Presentation	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background and Basis of Presentation [Text Block]	Background and Basis of Presentation No Registrant makes any representations as to the information related solely to CenterPoint Energy or the subsidiaries of CenterPoint Energy other than itself. General. Included in this combined Form 10-Q are the Interim Condensed Financial Statements of CenterPoint Energy, Houston Electric and CERC, which are referred to collectively as the Registrants. The Combined Notes to the Unaudited Condensed Consolidated Financial Statements apply to all Registrants unless otherwise indicated. The Interim Condensed Financial Statements are unaudited, omit certain financial statement disclosures and should be read with each of the Registrants’ 2017 Form 10-K. Background. CenterPoint Energy, Inc. is a public utility holding company. CenterPoint Energy’s operating subsidiaries, Houston Electric and CERC, own and operate electric transmission and distribution and natural gas distribution facilities, supply natural gas to commercial and industrial customers and electric and natural gas utilities and own interests in Enable as described below. • Houston Electric engages in the electric transmission and distribution business in the Texas Gulf Coast area that includes the city of Houston; and • CERC Corp. (i) owns and operates natural gas distribution systems in six states and (ii) obtains and offers competitive variable and fixed-price physical natural gas supplies and services primarily to commercial and industrial customers and electric and natural gas utilities in 33 states through its wholly-owned subsidiary, CES. As of June 30, 2018, CERC Corp. owned approximately 54.0% of the common units representing limited partner interests in Enable, which owns, operates and develops natural gas and crude oil infrastructure assets. As of June 30, 2018 , CenterPoint Energy also owned an aggregate of 14,520,000 Series A Preferred Units in Enable. As of June 30, 2018 , CenterPoint Energy and Houston Electric had VIEs consisting of the Bond Companies, which are consolidated. The consolidated VIEs are wholly-owned, bankruptcy-remote, special purpose entities that were formed specifically for the purpose of securitizing transition and system restoration-related property. Creditors of CenterPoint Energy and Houston Electric have no recourse to any assets or revenues of the Bond Companies. The bonds issued by these VIEs are payable only from and secured by transition and system restoration property, and the bondholders have no recourse to the general credit of CenterPoint Energy or Houston Electric. Basis of Presentation. The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The Interim Condensed Financial Statements reflect all normal recurring adjustments that are, in the opinion of management, necessary to present fairly the financial position, results of operations and cash flows for the respective periods. Amounts reported in the Condensed Statements of Consolidated Income are not necessarily indicative of amounts expected for a full-year period due to the effects of, among other things, (a) seasonal fluctuations in demand for energy and energy services, (b) changes in energy commodity prices, (c) timing of maintenance and other expenditures and (d) acquisitions and dispositions of businesses, assets and other interests. Certain prior year amounts have been reclassified to conform to the current year presentation. For a description of the Registrants’ reportable business segments, see Note 16 .

New Accounting Pronouncements

New Accounting Pronouncements	6 Months Ended
	Jun. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements [Text Block]	New Accounting Pronouncements The following table provides an overview of recently adopted or issued accounting pronouncements applicable to all the Registrants, unless otherwise noted. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2014-09- Revenue from Contracts with Customers (Topic 606) and related amendments This standard provides a comprehensive new revenue recognition model that requires revenue to be recognized in a manner that depicts the transfer of goods or services to a customer at an amount that reflects the consideration expected to be received in exchange for those goods or services. Transition method: modified retrospective January 1, 2018 Note 4 addresses the disclosure requirements. Adoption of the standard did not result in significant changes to revenue recognition. A substantial amount of the Registrants’ revenues are tariff and/or derivative based, which were not significantly impacted by these ASUs. ASU 2017-05- Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets This standard clarifies when and how to apply ASC 610-20, which was issued as part of ASU 2014-09. It amends or supersedes the guidance in ASC 350 and ASC 360 on determining a gain or loss recognized upon the derecognition of nonfinancial assets. Transition method: modified retrospective January 1, 2018 ASU 2017-05 eliminates industry specific guidance, including ASC 360-20 Property, Plant, and Equipment - Real Estate Sales, for the recognition of gains or losses upon the sale of in-substance real estate. CenterPoint Energy and CERC elected to apply the practical expedient upon adoption to only evaluate transactions that were not determined to be complete as of the date of adoption. Subsequent to adoption, gains or losses on sales or dilution events in CenterPoint Energy’s or CERC’s investment in Enable may result in gains or losses recognized in earnings. See Note 9 for further discussion. ASU 2016-01-Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ASU 2018-03-Technical Corrections and Improvements to Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This standard requires equity investments that do not result in consolidation and are not accounted for under the equity method to be measured at fair value and to recognize any changes in fair value in net income unless the investments qualify for the new practicability exception. It does not change the guidance for classifying and measuring investments in debt securities and loans. It also changes certain disclosure requirements and other aspects related to recognition and measurement of financial assets and financial liabilities. Transition method: cumulative-effect adjustment to beginning retained earnings, and two features prospective January 1, 2018 The adoption of this standard did not have an impact on the Registrants’ financial position, results of operations or cash flows. The Registrants elected the practicability exception for investments without a readily determinable fair value to be measured at cost. This includes the Series A Preferred Units in Enable, which were previously accounted for under the cost method. See Note 9 for further discussion. ASU 2016-15- Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments This standard provides clarifying guidance on the classification of certain cash receipts and payments in the statement of cash flows and eliminates the variation in practice related to such classifications. Transition method: retrospective January 1, 2018 The adoption did not have a material impact on the Registrants’ financial position, results of operations or disclosures. However, CenterPoint Energy’s and Houston Electric’s Condensed Statements of Consolidated Cash Flows reflect an increase in investing activities and a corresponding decrease in operating activities of $1 million and $3 million for the six months ended June 30, 2018 and 2017, respectively, due to the requirement that cash proceeds from COLI policies be classified as cash inflows from investing activity. ASU 2016-18- Statement of Cash Flows (Topic 230): Restricted Cash This standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. Transition method: retrospective January 1, 2018 The adoption of this standard did not have an impact on the Registrants’ financial position, results of operations or disclosures. However, CenterPoint Energy’s and Houston Electric’s Condensed Statements of Consolidated Cash Flows are reconciled to cash, cash equivalents and restricted cash, resulting in a decrease in investing activities of $2 million and an increase in investing activities of $8 million for the six months ended June 30, 2018 and 2017, respectively. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2017-01- Business Combinations (Topic 805): Clarifying the Definition of a Business This standard revises the definition of a business. If substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, then under ASU 2017-01, the asset or group of assets is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs to be more closely aligned with how outputs are described in ASC 606. Transition method: prospective January 1, 2018 The adoption of this revised definition will reduce the number of transactions that are accounted for as a business combination, and therefore may have a potential impact on the Registrants’ accounting for future acquisitions. ASU 2017-04- Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This standard eliminates Step 2 of the goodwill impairment test, which required a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s and CERC’s future calculation of goodwill impairments if an impairment is identified. ASU 2017-07- Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This standard requires an employer to report the service cost component of the net periodic pension cost and postretirement benefit cost in the same line item(s) as other employee compensation costs arising from services rendered during the period; all other components will be presented separately from the line item(s) that includes the service cost and outside of any subtotal of operating income. In addition, only the service cost component will be eligible for capitalization in assets. Transition method: retrospective for the presentation of the service cost component and other components; prospective for the capitalization of the service cost component January 1, 2018 The adoption of this standard did not have a material impact on the Registrants’ financial position, results of operations, cash flows or disclosures; however, it resulted in the increases to operating income and corresponding decreases to other income reported in the table below. Other components previously capitalized in assets will be recorded as regulatory assets in the Registrants’ rate-regulated businesses, prospectively. ASU 2017-09- Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting This standard clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. Entities will apply the modification accounting guidance if the value, vesting conditions or classification of the award changes. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s accounting for future changes to share-based payment awards. The table below reflects the impact of adoption of ASU 2017-07: Three Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 15 $ 8 $ 4 $ 17 $ 7 $ 6 Decrease to other income 15 8 4 17 7 6 Six Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 29 $ 15 $ 8 $ 34 $ 15 $ 11 Decrease to other income 29 15 8 34 15 11 Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2016-02- Leases (Topic 842) and related amendments ASU 2018-01- Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842 ASU 2016-02 provides a comprehensive new lease model that requires lessees to recognize assets and liabilities for most leases and would change certain aspects of lessor accounting. Transition method : modified retrospective ASU 2018-01 allows entities to elect not to assess whether existing land easements that were not previously accounted for in accordance with ASC 840 Leases under ASC 842 Leases when transitioning to the new leasing standard. January 1, 2019 Early adoption is permitted The Registrants will elect the practical expedient on existing easements provided by ASU 2018-01 and are evaluating other available transitional practical expedients. The Registrants are in the process of reviewing contracts to identify leases as defined in ASU 2016-02 and expect to recognize on the statements of financial position right-of-use assets and lease liabilities for the majority of their respective leases that are currently classified as operating leases. The Registrants are continuing to assess the impact that adoption of these standards will have on their financial position, results of operations, cash flows and disclosures. ASU 2017-12- Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities This standard expands an entity’s ability to hedge nonfinancial and financial risk components and reduce complexity in fair value hedges of interest rate risk. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness, eases certain documentation and assessment requirements and updates the presentation and disclosure requirements. Transition method: cumulative-effect adjustment for elimination of the separate measurement of ineffectiveness; prospective for presentation and disclosure January 1, 2019 Early adoption is permitted The Registrants are currently assessing the impact that adoption of this standard will have on their financial position, results of operations, cash flows and disclosures. ASU 2018-02-Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA and requires entities to provide certain disclosures regarding stranded tax effects. Transition method: either in the period of adoption or retrospective January 1, 2019 Early adoption is permitted The adoption of this standard will allow the Registrants to reclass stranded deferred tax adjustments primarily related to benefit plans from other comprehensive income to retained earnings. The Registrants are currently assessing the impact that adoption of this standard will have on their financial position and disclosures. Management believes that other recently adopted standards and recently issued standards that are not yet effective will not have a material impact on the Registrants’ financial position, results of operations or cash flows upon adoption.

Proposed Merger with Vectren (C

Proposed Merger with Vectren (CenterPoint Energy)	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Proposed Merger with Vectren (CenterPoint Energy) [Text Block]	Proposed Merger with Vectren (CenterPoint Energy) On April 21, 2018, CenterPoint Energy entered into the Merger Agreement. Under the terms of the Merger Agreement, CenterPoint Energy will acquire Vectren for approximately $6 billion in cash. Upon closing, Vectren will become a wholly-owned subsidiary of CenterPoint Energy. Pursuant to the Merger Agreement, upon the closing of the Merger, each share of Vectren common stock issued and outstanding immediately prior to the closing will be converted automatically into the right to receive $72.00 in cash per share. CenterPoint Energy expects to finance the Merger with a combination of debt, equity-linked and equity issuances and has obtained commitments by lenders for a Bridge Facility to provide flexibility for the timing of the long-term acquisition financing and fund, in part, amounts payable by CenterPoint Energy in connection with the Merger. All outstanding debt held by Vectren and its subsidiaries will be assumed by CenterPoint Energy at the closing of the Merger. As of June 30, 2018, Vectren and its subsidiaries had outstanding $248 million of short-term debt and $2.0 billion of long-term debt, including current maturities. It is anticipated that Vectren and its subsidiaries will have approximately $2.5 billion of outstanding short-term and long-term debt as of December 31, 2018. Consummation of the Merger is conditioned upon approval by federal regulatory commissions, orders from state regulatory commissions, expiration or termination of the applicable HSR waiting period and approval of the Merger by Vectren shareholders. In June 2018, CenterPoint Energy and Vectren (i) submitted their filings with the FERC and the FCC and pursuant to the HSR Act and (ii) initiated informational proceedings with regulators in Indiana and Ohio. On June 26, 2018, CenterPoint Energy and Vectren received notice from the FTC granting early termination of the waiting period under the HSR Act in connection with the Merger. On July 16, 2018, Vectren filed its definitive proxy statement, as supplemented, with the SEC for a special meeting of its shareholders to be held on August 28, 2018 in connection with the Merger. The Merger Agreement contains termination rights for both CenterPoint Energy and Vectren, and provides that, upon termination of the Merger Agreement under specified circumstances, CenterPoint Energy would be required to pay a termination fee of $210 million to Vectren and Vectren would be required to pay CenterPoint Energy a termination fee of $150 million . Subject to receipt of required regulatory and statutory approvals and satisfaction and/or waiver of the closing conditions, CenterPoint Energy continues to anticipate closing the Merger in the first quarter of 2019.

Revenue Recognition

Revenue Recognition	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition [Text Block]	Revenue Recognition The Registrants adopted ASC 606 and all related amendments on January 1, 2018 using the modified retrospective method for those contracts that were not completed as of the date of adoption. Application of the new revenue standard did not result in a cumulative effect adjustment to the opening balance of retained earnings. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. The adoption of the new standard did not have a material impact on the Registrants’ financial position, results of operations or cash flows. In accordance with ASC 606, revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which the Registrants expect to be entitled to receive in exchange for these goods or services. Contract assets and liabilities are not material. The following tables disaggregate revenues by reportable business segment and major source: CenterPoint Energy Three Months Ended June 30, 2018 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 860 $ 509 $ 78 $ 2 $ 1,449 $ 758 $ 463 $ 116 $ 1 $ 1,338 Derivatives income — — 782 — 782 — — 815 — 815 Other (3) (6 ) (14 ) — 2 (18 ) (6 ) 14 — 2 10 Eliminations — (8 ) (19 ) — (27 ) — (7 ) (13 ) — (20 ) Total revenues $ 854 $ 487 $ 841 $ 4 $ 2,186 $ 752 $ 470 $ 918 $ 3 $ 2,143 Six Months Ended June 30, 2018 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 1,621 $ 1,695 $ 256 $ 3 $ 3,575 $ 1,402 $ 1,388 $ 258 $ 2 $ 3,050 Derivatives income (4 ) — 1,889 — 1,885 1 — 1,869 — 1,870 Other (3) (12 ) (47 ) — 5 (54 ) (12 ) 5 — 5 (2 ) Eliminations — (18 ) (47 ) — (65 ) — (16 ) (24 ) — (40 ) Total revenues $ 1,605 $ 1,630 $ 2,098 $ 8 $ 5,341 $ 1,391 $ 1,377 $ 2,103 $ 7 $ 4,878 Houston Electric Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Revenue from contracts $ 860 $ 758 $ 1,621 $ 1,402 Other (3) (6 ) (6 ) (12 ) (12 ) $ 854 $ 752 $ 1,609 $ 1,390 CERC Three Months Ended June 30, 2018 2017 Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 509 $ 78 $ — $ 587 $ 463 $ 116 $ — $ 579 Derivatives income — 782 — 782 — 815 — 815 Other (3) (14 ) — — (14 ) 14 — (1 ) 13 Eliminations (8 ) (19 ) — (27 ) (7 ) (13 ) — (20 ) Total revenues $ 487 $ 841 $ — $ 1,328 $ 470 $ 918 $ (1 ) $ 1,387 Six Months Ended June 30, 2018 2017 Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 1,695 $ 256 $ — $ 1,951 $ 1,388 $ 258 $ — $ 1,646 Derivatives income — 1,889 — 1,889 — 1,869 — 1,869 Other (3) (47 ) — — (47 ) 5 — — 5 Eliminations (18 ) (47 ) — (65 ) (16 ) (24 ) — (40 ) Total revenues $ 1,630 $ 2,098 $ — $ 3,728 $ 1,377 $ 2,103 $ — $ 3,480 (1) Reflected in Utility revenues in the Condensed Statements of Consolidated Income. (2) Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income. (3) Primarily consists of income from ARPs and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. The Registrants recognize ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period. Revenues from Contracts with Customers Electric Transmission & Distribution. Houston Electric distributes electricity to customers over time and customers consume the electricity when delivered. Revenue, consisting of both volumetric and fixed tariff rates set by the PUCT, is recognized as electricity is delivered and represents amounts both billed and unbilled. Discretionary services requested by customers are provided at a point in time with control transferring upon the completion of the service. Revenue for discretionary services is recognized upon completion of service based on the tariff rates set by the PUCT. Payments for electricity distribution and discretionary services are aggregated and received on a monthly basis. Houston Electric performs transmission services over time as a stand-ready obligation to provide a reliable network of transmission systems. Revenue is recognized upon time elapsed, and the monthly tariff rate set by the PUCT. Payments are received on a monthly basis. Natural Gas Distribution. CERC distributes and transports natural gas to customers over time, and customers consume the natural gas when delivered. Revenue, consisting of both volumetric and fixed tariff rates set by the state governing agency for that service area, is recognized as natural gas is delivered and represents amounts both billed and unbilled. Discretionary services requested by the customer are satisfied at a point in time and revenue is recognized upon completion of service and the tariff rates set by the applicable state regulator. Payments of natural gas distribution, transportation and discretionary services are aggregated and received on a monthly basis. Energy Services. The majority of CES natural gas sales contracts are considered a derivative, as the contracts typically have a stated minimum or contractual volume of delivery. For contracts in which CES delivers the full requirement of the natural gas needed by the customer and a volume is not stated, a contract as defined under ASC 606 is created upon the customer’s exercise of its option to take natural gas. CES supplies natural gas to retail customers over time as customers consume the natural gas when delivered. For wholesale customers, CES supplies natural gas at a point in time because the wholesale customer is presumed to have storage capabilities. Control is transferred to both types of customers upon delivery of natural gas. Revenue is recognized on a monthly basis based on the estimated volume of natural gas delivered and the price agreed upon with the customer. Payments are received on a monthly basis. AMAs are natural gas sales contracts under which CES also assumes management of a customer’s physical storage and/or transportation capacity. AMAs have two distinct performance obligations, which consist of natural gas sales and natural gas delivery because delivery could occur separate from the sale of natural gas (e.g., from storage to customer premises). Most AMAs’ natural gas sales performance obligations are accounted for as embedded derivatives. The transaction price is allocated between the sale of natural gas and the delivery based on the stand-alone selling price as stated in the contract. CES performs natural gas delivery over time as customers take delivery of the natural gas and recognizes revenue on an aggregated monthly basis based on the volume of natural gas delivered and the fees stated within the contract. Payments are received on a monthly basis. Practical Expedients and Exemption. Sales taxes and other similar taxes collected from customers are excluded from the transaction price.

Employee Benefit Plans

Employee Benefit Plans	6 Months Ended
	Jun. 30, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans [Text Block]	Employee Benefit Plans The Registrants’ net periodic cost, before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes, includes the following components relating to pension and postretirement benefits: Pension Benefits (CenterPoint Energy) Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Service cost (1) $ 9 $ 9 $ 18 $ 18 Interest cost (2) 19 22 39 44 Expected return on plan assets (2) (26 ) (24 ) (53 ) (48 ) Amortization of prior service cost (2) 2 3 4 5 Amortization of net loss (2) 11 15 22 29 Net periodic cost $ 15 $ 25 $ 30 $ 48 Postretirement Benefits Three Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ 1 $ — $ — $ 1 $ — $ — Interest cost (2) 4 2 1 4 2 1 Expected return on plan assets (2) (2 ) (1 ) (1 ) (2 ) (1 ) — Amortization of prior service cost (credit) (2) (1 ) (2 ) 1 (1 ) (1 ) 1 Net periodic cost $ 2 $ (1 ) $ 1 $ 2 $ — $ 2 Six Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ 1 $ — $ — $ 1 $ — $ — Interest cost (2) 7 4 2 8 4 2 Expected return on plan assets (2) (3 ) (2 ) (1 ) (3 ) (2 ) — Amortization of prior service cost (credit) (2) (2 ) (3 ) 1 (2 ) (2 ) 1 Net periodic cost $ 3 $ (1 ) $ 2 $ 4 $ — $ 3 (1) Included in Operation and maintenance expense in the Registrants’ Condensed Statements of Consolidated Income. (2) Included in Other, net in the Registrants’ Condensed Statements of Consolidated Income. Changes in accumulated other comprehensive loss related to defined benefit and postretirement plans are as follows: CenterPoint Energy Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Beginning Balance $ (65 ) $ (71 ) $ (66 ) $ (72 ) Amounts reclassified from accumulated other comprehensive loss: Prior service cost (1) 1 1 1 1 Actuarial losses (1) 1 1 3 3 Tax expense — (1 ) (1 ) (2 ) Net current period other comprehensive income 2 1 3 2 Ending Balance $ (63 ) $ (70 ) $ (63 ) $ (70 ) (1) These accumulated other comprehensive components are included in the computation of net periodic cost. The table below reflects the expected contributions to be made to the pension plans and postretirement benefit plan during 2018: CenterPoint Energy Houston Electric CERC (in millions) Expected minimum contribution to pension plans during 2018 $ 67 $ — $ — Expected contribution to postretirement benefit plan in 2018 16 10 5 The table below reflects the contributions made to the pension plans and postretirement benefit plan during 2018: Three Months Ended June 30, 2018 Six Months Ended June 30, 2018 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Pension plans $ 2 $ — $ — $ 64 $ — $ — Postretirement benefit plan 3 2 1 7 4 2

Regulatory Accounting

Regulatory Accounting	6 Months Ended
	Jun. 30, 2018
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Regulatory Accounting [Text Block]	Regulatory Accounting The following is a list of regulatory assets and liabilities reflected on the Registrants’ Condensed Consolidated Balance Sheets: June 30, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC Regulatory Assets: (in millions) Current regulatory assets (1) $ 55 $ — $ 55 $ 130 $ — $ 130 Non-current regulatory assets: Securitized regulatory assets 1,293 1,293 — 1,590 1,590 — Unrecognized equity return (2) (242 ) (242 ) — (287 ) (287 ) — Unamortized loss on reacquired debt 72 72 — 75 75 — Pension and postretirement-related regulatory asset (3) 623 32 18 646 31 20 Hurricane Harvey restoration costs (4) 63 56 7 64 58 6 Regulatory assets related to TCJA (5) 48 33 15 48 33 15 Other long-term regulatory assets (6) 210 77 133 211 70 140 Total non-current regulatory assets 2,067 1,321 173 2,347 1,570 181 Total regulatory assets 2,122 1,321 228 2,477 1,570 311 Regulatory Liabilities: Current regulatory liabilities (7) 43 6 37 24 22 2 Non-current regulatory liabilities: Regulatory liabilities related to TCJA (5) 1,389 885 504 1,354 862 492 Estimated removal costs 885 279 606 878 285 593 Other long-term regulatory liabilities 247 101 146 232 116 116 Total non-current regulatory liabilities 2,521 1,265 1,256 2,464 1,263 1,201 Total regulatory liabilities 2,564 1,271 1,293 2,488 1,285 1,203 Total regulatory assets and liabilities, net $ (442 ) $ 50 $ (1,065 ) $ (11 ) $ 285 $ (892 ) (1) Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ Condensed Consolidated Balance Sheets. (2) The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended June 30, 2018 and 2017 , CenterPoint Energy and Houston Electric recognized approximately $24 million and $10 million , respectively, of the allowed equity return. During the six months ended June 30, 2018 and 2017 , CenterPoint Energy and Houston Electric recognized approximately $45 million and $17 million , respectively, of the allowed equity return. The timing of CenterPoint Energy’s and Houston Electric’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months. (3) Includes a portion of NGD’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates that is being deferred for rate making purposes, of which $5 million and $7 million as of June 30, 2018 and December 31, 2017 , respectively, were not earning a return. (4) The Registrants are not earning a return on Hurricane Harvey restoration costs. (5) The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities. (6) Other long-term regulatory assets that are not earning a return were not material as of June 30, 2018 and December 31, 2017 . (7) Current regulatory liabilities are included in Other current liabilities in the Registrants’ Condensed Consolidated Balance Sheets.

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments [Text Block]	Derivative Instruments The Registrants are exposed to various market risks. These risks arise from transactions entered into in the normal course of business. The Registrants utilize derivative instruments such as physical forward contracts, swaps and options to mitigate the impact of changes in commodity prices, weather and interest rates on its operating results and cash flows. Such derivatives are recognized in the Registrants’ Condensed Consolidated Balance Sheets at their fair value unless the Registrants elect the normal purchase and sales exemption for qualified physical transactions. A derivative may be designated as a normal purchase or normal sale if the intent is to physically receive or deliver the product for use or sale in the normal course of business. CenterPoint Energy has a Risk Oversight Committee composed of corporate and business segment officers that oversees commodity price, weather and credit risk activities, including the Registrants’ marketing, risk management services and hedging activities. The committee’s duties are to establish the Registrants’ commodity risk policies, allocate board-approved commercial risk limits, approve the use of new products and commodities, monitor positions and ensure compliance with the Registrants’ commercial risk management policy and procedures and limits established by CenterPoint Energy’s Board of Directors. The Registrants’ policies prohibit the use of leveraged financial instruments. A leveraged financial instrument, for this purpose, is a transaction involving a derivative whose financial impact will be based on an amount other than the notional amount or volume of the instrument. (a) Non-Trading Activities Derivative Instruments. CenterPoint Energy and CERC, through CES, enter into certain derivative instruments to mitigate the effects of commodity price movements. Certain financial instruments used to hedge portions of the natural gas inventory of the Energy Services business segment are designated as fair value hedges for accounting purposes. All other financial instruments do not qualify or are not designated as cash flow or fair value hedges. Weather Hedges. CenterPoint Energy and CERC have weather normalization or other rate mechanisms that mitigate the impact of weather on NGD in Arkansas, Louisiana, Mississippi, Minnesota and Oklahoma. NGD and electric operations in Texas do not have such mechanisms, although fixed customer charges are historically higher in Texas for NGD compared to its other jurisdictions. As a result, fluctuations from normal weather may have a positive or negative effect on NGD’s results in Texas and on electric operations’ results in its service territory. CenterPoint Energy and CERC, as applicable, enter into winter season weather hedges from time to time for certain NGD jurisdictions and electric operations’ service territory to mitigate the effect of fluctuations from normal weather on results of operations and cash flows. These weather hedges are based on heating degree days at 10 -year normal weather. Houston Electric does not enter into weather hedges. The table below summarizes CenterPoint Energy’s and CERC’s current weather hedge activity: Three Months Ended June 30, Six Months Ended June 30, Jurisdiction Winter Season Bilateral Cap 2018 2017 2018 2017 (in millions) Certain NGD jurisdictions 2018 – 2019 $ 9 $ — $ — $ — $ — Certain NGD jurisdictions 2017 – 2018 8 — — — — Total CERC (1) — — — — Electric operations’ service territory 2018 – 2019 8 — — — — Electric operations’ service territory 2017 – 2018 9 — — (4 ) — Electric operations’ service territory 2016 – 2017 9 — — — 1 Total CenterPoint Energy (1) $ — $ — $ (4 ) $ 1 (1) Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income. Hedging of Interest Expense for Future Debt Issuances. In January and February 2018, Houston Electric entered into forward interest rate agreements with multiple counterparties, having an aggregate notional amount of $200 million . These agreements were executed to hedge, in part, volatility in the 30-year U.S. treasury rate by reducing Houston Electric’s exposure to variability in cash flows related to interest payments of Houston Electric’s $400 million issuance of fixed rate debt in February 2018. These forward interest rate agreements were designated as cash flow hedges. Accordingly, the effective portion of realized gains associated with the forward interest rate agreements, which totaled approximately $5 million , is a component of accumulated other comprehensive income in 2018 and will be amortized over the life of the fixed rate debt. In March 2018, CERC Corp. entered into forward interest rate agreements with multiple counterparties, having an aggregate notional amount of $450 million . These agreements were executed to hedge, in part, volatility in the 5-year and 10-year U.S. treasury rates by reducing CERC Corp.’s exposure to variability in cash flows related to interest payments of CERC Corp.’s $600 million issuance of fixed rate debt in March 2018. These forward interest rate agreements were designated as cash flow hedges. Accordingly, the effective portion of realized losses associated with the forward interest rate agreements, which totaled less than $1 million , is a component of accumulated other comprehensive income in 2018 and will be amortized over the life of the fixed rate debt. (b) Derivative Fair Values and Income Statement Impacts The following tables present information about derivative instruments and hedging activities. The first two tables provide a balance sheet overview of Derivative Assets and Liabilities, while the last table provides a breakdown of the related income statement impacts. Fair Value of Derivative Instruments (CenterPoint Energy and CERC) June 30, 2018 December 31, 2017 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivative Assets Fair Value Derivative Liabilities Fair Value Derivatives designated as fair value hedges: (in millions) Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities $ — $ 3 $ 13 $ 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 76 2 114 4 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 46 — 44 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 23 64 38 78 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 15 41 9 24 Total CERC 160 110 218 107 Indexed debt securities derivative Current Liabilities — 641 — 668 Total CenterPoint Energy $ 160 $ 751 $ 218 $ 775 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,862 Bcf or a net 268 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of June 30, 2018 and December 31, 2017 , respectively. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure. (2) Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $82 million asset and a $130 million asset as of June 30, 2018 and December 31, 2017 , respectively, as shown on CenterPoint Energy’s and CERC’s Condensed Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, impacted by collateral netting of $32 million and $19 million , respectively. (3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable. Offsetting of Natural Gas Derivative Assets and Liabilities (CenterPoint Energy and CERC) June 30, 2018 December 31, 2017 Gross Amounts Recognized (1) Gross Amounts Offset in the Consolidated Balance Sheets Net Amount Presented in the Consolidated Balance Sheets (2) Gross Amounts Recognized (1) Gross Amounts Offset in the Consolidated Balance Sheets Net Amount Presented in the Consolidated Balance Sheets (2) (in millions) Current Assets: Non-trading derivative assets $ 99 $ (25 ) $ 74 $ 165 $ (55 ) $ 110 Other Assets: Non-trading derivative assets 61 (15 ) 46 53 (9 ) 44 Current Liabilities: Non-trading derivative liabilities (69 ) 43 (26 ) (83 ) 63 (20 ) Other Liabilities: Non-trading derivative liabilities (41 ) 29 (12 ) (24 ) 20 (4 ) Total $ 50 $ 32 $ 82 $ 111 $ 19 $ 130 (1) Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements. (2) The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default. Realized and unrealized gains and losses on natural gas derivatives are recognized in the Condensed Statements of Consolidated Income as revenue for physical sales derivative contracts and as natural gas expense for financial natural gas derivatives and physical purchase natural gas derivatives. Realized and unrealized gains and losses on indexed debt securities are recorded as Other Income (Expense) in the Condensed Statements of Consolidated Income. Hedge ineffectiveness is recorded as a component of natural gas expense and primarily results from differences in the location of the derivative instrument and the hedged item. Basis ineffectiveness arises from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the hedge instruments. The impact of natural gas derivatives designated as fair value hedges, the related hedged item, and natural gas derivatives not designated as hedging instruments are presented in the table below. Income Statement Impact of Derivative Activity (CenterPoint Energy and CERC) Three Months Ended June 30, Six Months Ended June 30, Income Statement Location 2018 2017 2018 2017 Derivatives designated as fair value hedges: (in millions) Natural gas derivatives Gains (Losses) in Non-utility natural gas expense $ 13 $ 3 $ 13 $ 12 Natural gas inventory Gains (Losses) in Non-utility natural gas expense (12 ) (4 ) (14 ) (14 ) Total CenterPoint Energy and CERC (1) $ 1 $ (1 ) $ (1 ) $ (2 ) Derivatives not designated as hedging instruments: Natural gas derivatives Gains (Losses) in Non-utility revenues $ 11 $ 36 $ 68 $ 132 Natural gas derivatives Gains (Losses) in Non-utility natural gas expense (9 ) (9 ) (78 ) (82 ) Total CERC 2 27 (10 ) 50 Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (254 ) (13 ) (272 ) (23 ) Total CenterPoint Energy $ (252 ) $ 14 $ (282 ) $ 27 (1) Hedge ineffectiveness results from the basis ineffectiveness discussed above, and excludes the impact to natural gas expense from timing ineffectiveness. Timing ineffectiveness arises due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity. As the commodity contract nears the settlement date, spot-to-forward price differences should converge, which should reduce or eliminate the impact of this ineffectiveness on natural gas expense. (c) Credit Risk Contingent Features CenterPoint Energy and CERC enter into financial derivative contracts containing material adverse change provisions. These provisions could require CenterPoint Energy or CERC to post additional collateral if the S&P or Moody’s credit ratings of CenterPoint Energy, Inc. or its subsidiaries, including CERC Corp., are downgraded. CenterPoint Energy and CERC June 30, December 31, 2017 (in millions) Aggregate fair value of derivatives containing material adverse change provisions in a net liability position $ 2 $ 2 Fair value of collateral already posted — — Additional collateral required to be posted if credit risk contingent features triggered 1 2

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements [Text Block]	Fair Value Measurements Assets and liabilities that are recorded at fair value in the Registrants’ Condensed Consolidated Balance Sheets are categorized based upon the level of judgment associated with the inputs used to measure their value. Hierarchical levels, as defined below and directly related to the amount of subjectivity associated with the inputs to fair valuations of these assets and liabilities, are as follows: Level 1: Inputs are unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date. The types of assets carried at Level 1 fair value generally are exchange-traded derivatives and equity securities, as well as natural gas inventory that has been designated as the hedged item in a fair value hedge. Level 2: Inputs, other than quoted prices included in Level 1, are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar instruments in active markets, and inputs other than quoted prices that are observable for the asset or liability. Fair value assets and liabilities that are generally included in this category are derivatives with fair values based on inputs from actively quoted markets. A market approach is utilized to value the Registrants’ Level 2 assets or liabilities. Level 3: Inputs are unobservable for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. Unobservable inputs reflect the Registrants’ judgments about the assumptions market participants would use in pricing the asset or liability since limited market data exists. The Registrants develop these inputs based on the best information available, including the Registrants’ own data. A market approach is utilized to value the Registrants’ Level 3 assets or liabilities. As of June 30, 2018 , CenterPoint Energy’s and CERC’s Level 3 assets and liabilities are comprised of physical natural gas forward contracts and options and CenterPoint Energy’s indexed debt securities. Level 3 physical natural gas forward contracts and options are valued using a discounted cash flow model which includes illiquid forward price curve locations (ranging from $1.04 to $3.31 per MMBtu) as an unobservable input. CenterPoint Energy’s and CERC’s Level 3 physical natural gas forward contracts and options derivative assets and liabilities consist of both long and short positions (forwards and options) and their fair value is sensitive to forward prices. If forward prices decrease, CenterPoint Energy’s and CERC’s long forwards and options lose value whereas their short forwards and options gain in value. CenterPoint Energy’s Level 3 indexed debt securities derivative is valued using an option model and a discounted cash flow model, which uses projected dividends on the ZENS-Related Securities and a discount rate as unobservable inputs. An increase and a decrease in the unobservable inputs will generally decrease and increase the value of the indexed debt securities derivative, respectively. The Registrants determine the appropriate level for each financial asset and liability on a quarterly basis and recognize transfers between levels at the end of the reporting period. For the six months ended June 30, 2018 , there were no transfers between Level 1 and 2. The Registrants also recognize purchases of Level 3 financial assets and liabilities at their fair market value at the end of the reporting period. The following tables present information about the Registrants’ assets and liabilities (including derivatives that are presented net) measured at fair value on a recurring basis and indicate the fair value hierarchy of the valuation techniques utilized by the Registrants to determine such fair value. CenterPoint Energy June 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting (1) Total Level 1 Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 586 $ — $ — $ — $ 586 $ 963 $ — $ — $ — $ 963 Investments, including money market funds (2) 70 — — — 70 68 — — — 68 Natural gas derivatives (3) — 142 18 (40 ) 120 — 161 57 (64 ) 154 Hedged portion of natural gas inventory — — — — — 14 — — — 14 Total assets $ 656 $ 142 $ 18 $ (40 ) $ 776 $ 1,045 $ 161 $ 57 $ (64 ) $ 1,199 Liabilities Indexed debt securities derivative $ — $ — $ 641 $ — $ 641 $ — $ — $ 668 $ — $ 668 Natural gas derivatives (3) — 105 5 (72 ) 38 — 96 11 (83 ) 24 Hedged portion of natural gas inventory 1 — — — 1 — — — — — Total liabilities $ 1 $ 105 $ 646 $ (72 ) $ 680 $ — $ 96 $ 679 $ (83 ) $ 692 Houston Electric June 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting Total Level 1 Level 2 Level 3 Netting Total Assets (in millions) Investments, including money market funds (2) $ 52 $ — $ — $ — $ 52 $ 51 $ — $ — $ — $ 51 Total assets $ 52 $ — $ — $ — $ 52 $ 51 $ — $ — $ — $ 51 CERC June 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting (1) Total Level 1 Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 2 $ — $ — $ — $ 2 $ 3 $ — $ — $ — $ 3 Investments, including money market funds (2) 11 — — — 11 11 — — — 11 Natural gas derivatives (3) — 142 18 (40 ) 120 — 161 57 (64 ) 154 Hedged portion of natural gas inventory — — — — — 14 — — — 14 Total assets $ 13 $ 142 $ 18 $ (40 ) $ 133 $ 28 $ 161 $ 57 $ (64 ) $ 182 Liabilities Natural gas derivatives (3) $ — $ 105 $ 5 $ (72 ) $ 38 $ — $ 96 $ 11 $ (83 ) $ 24 Hedged portion of natural gas inventory 1 — — — 1 — — — — — Total liabilities $ 1 $ 105 $ 5 $ (72 ) $ 39 $ — $ 96 $ 11 $ (83 ) $ 24 (1) Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy and CERC to settle positive and negative positions and also include cash collateral of $32 million and $19 million as of June 30, 2018 and December 31, 2017 , respectively, posted with the same counterparties. (2) Amounts are included in Prepaid expenses and other current assets in the Condensed Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable. The following table presents additional information about assets or liabilities, including derivatives that are measured at fair value on a recurring basis for which CenterPoint Energy and CERC have utilized Level 3 inputs to determine fair value: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC (in millions) Beginning balance $ (662 ) $ 12 $ (700 ) $ 27 $ (622 ) $ 46 $ (704 ) $ 13 Total gains (losses) (11 ) 1 (6 ) 7 (16 ) 3 — 23 Total settlements 44 (1 ) — — 11 (35 ) (4 ) (4 ) Transfers into Level 3 1 1 1 1 1 1 2 2 Transfers out of Level 3 — — (7 ) (7 ) (2 ) (2 ) (6 ) (6 ) Ending balance (1) $ (628 ) $ 13 $ (712 ) $ 28 $ (628 ) $ 13 $ (712 ) $ 28 The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date: $ (9 ) $ 3 $ (9 ) $ 4 $ (23 ) $ (4 ) $ (2 ) $ 21 (1) CenterPoint Energy and CERC did not have significant Level 3 sales or purchases during either of the three or six months ended June 30, 2018 or 2017 . Estimated Fair Value of Financial Instruments The fair values of cash and cash equivalents, investments in debt and equity securities classified as “trading” and short-term borrowings are estimated to be approximately equivalent to carrying amounts and have been excluded from the table below. The carrying amounts of non-trading derivative assets and liabilities and CenterPoint Energy’s ZENS indexed debt securities derivative are stated at fair value and are excluded from the table below. The fair value of each debt instrument is determined by multiplying the principal amount of each debt instrument by a combination of historical trading prices and comparable issue data. These liabilities, which are not measured at fair value in the Registrants’ Condensed Consolidated Balance Sheets, but for which the fair value is disclosed, would be classified as Level 2 in the fair value hierarchy. June 30, 2018 December 31, 2017 CenterPoint Energy (1) Houston Electric (1) CERC CenterPoint Energy (1) Houston Electric (1) CERC Long-term debt, including current maturities (in millions) Carrying amount $ 8,256 $ 4,919 $ 2,722 $ 8,679 $ 4,753 $ 2,457 Fair value 8,470 4,991 2,876 9,220 5,034 2,708 (1) Includes Securitization Bond debt.

Unconsolidated Affiliate (Cente

Unconsolidated Affiliate (CenterPoint Energy and CERC)	6 Months Ended
	Jun. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Unconsolidated Affiliate (CenterPoint Energy and CERC) [Text Block]	Unconsolidated Affiliate (CenterPoint Energy and CERC) CenterPoint Energy and CERC have the ability to significantly influence the operating and financial policies of Enable, a publicly traded MLP, and, accordingly, account for the investment in Enable’s common units using the equity method of accounting for in-substance real estate. Upon the adoption of ASU 2014-09 and ASU 2017-05 on January 1, 2018, CenterPoint Energy and CERC evaluated transactions in the investment in Enable that occurred prior to January 1, 2018 (the effective date) and concluded a cumulative effect adjustment to the opening balance of retained earnings was not required. See Note 2 for further discussion. CenterPoint Energy’s and CERC’s maximum exposure to loss related to Enable, a VIE in which CenterPoint Energy and CERC are not the primary beneficiaries, is limited to the equity investment, the Series A Preferred Unit investment and outstanding current accounts receivable from Enable. Limited Partner Interest and Units Held in Enable: June 30, 2018 Limited Partner Interest (1) Common Units Series A Preferred Units (2) CERC Corp. 54.0 % 233,856,623 — OGE 25.6 % 110,982,805 — Public unitholders 20.4 % 88,225,208 — CenterPoint Energy — — 14,520,000 Total units outstanding 100.0 % 433,064,636 14,520,000 (1) Excluding the Series A Preferred Units owned by CenterPoint Energy. (2) The carrying amount of the Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both June 30, 2018 and December 31, 2017 . No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion. Generally, sales to any person or entity (including a series of sales to the same person or entity) of more than 5% of the aggregate of the common units CERC Corp. owns in Enable or sales to any person or entity (including a series of sales to the same person or entity) by OGE of more than 5% of the aggregate of the common units it owns in Enable are subject to mutual rights of first offer and first refusal set forth in Enable’s Agreement of Limited Partnership. Enable is controlled jointly by CERC Corp. and OGE, and each own 50% of the management rights in the general partner of Enable. Sale of CERC Corp.’s or OGE’s ownership interests in Enable’s general partner to a third party is subject to mutual rights of first offer and first refusal, and CERC Corp. is not permitted to dispose of less than all of its interest in Enable’s general partner. Distributions Received from Enable: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Investment in Enable common units $ 75 $ 75 $ 149 $ 149 Total CERC 75 75 149 149 Investment in Enable Series A Preferred Units 9 9 18 18 Total CenterPoint Energy $ 84 $ 84 $ 167 $ 167 As of June 30, 2018 , CERC Corp. and OGE also owned 40% and 60% , respectively, of the incentive distribution rights held by the general partner of Enable. Enable is expected to pay a minimum quarterly distribution of $0.2875 per common unit on its outstanding common units to the extent it has sufficient cash from operations after establishment of cash reserves and payment of fees and expenses, including payments to its general partner and its affiliates, within 60 days after the end of each quarter. If cash distributions to Enable’s unitholders exceed $0.330625 per common unit in any quarter, the general partner will receive increasing percentages or incentive distributions rights, up to 50% , of the cash Enable distributes in excess of that amount. In certain circumstances the general partner of Enable will have the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable’s cash distributions at the time of the exercise of this reset election. To date, no incentive distributions have been made. Transactions with Enable (CenterPoint Energy and CERC): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Reimbursement of transition services (1) $ 1 $ 1 $ 3 $ 3 Natural gas expenses, including transportation and storage costs 29 24 66 57 (1) Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement. June 30, 2018 December 31, 2017 (in millions) Accounts receivable for amounts billed for transition services $ 3 $ 1 Accounts payable for natural gas purchases from Enable 8 13 Summarized unaudited consolidated income information for Enable is as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Operating revenues $ 805 $ 626 $ 1,553 $ 1,292 Cost of sales, excluding depreciation and amortization 444 279 819 587 Operating income 126 122 265 262 Net income attributable to Enable 86 86 191 197 Reconciliation of Equity in Earnings, net: CenterPoint Energy’s and CERC’s interest $ 46 $ 47 $ 103 $ 107 Basis difference amortization (1) 12 12 24 24 CenterPoint Energy’s and CERC’s equity in earnings, net $ 58 $ 59 $ 127 $ 131 (1) Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s and CERC’s share of Enable’s earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s and CERC’s original investment in Enable and their underlying equity in Enable’s net assets. The basis difference is amortized over approximately 31 years, the average life of the assets to which the basis difference is attributed. Summarized unaudited consolidated balance sheet information for Enable is as follows: June 30, December 31, 2017 (in millions) Current assets $ 432 $ 416 Non-current assets 11,360 11,177 Current liabilities 1,258 1,279 Non-current liabilities 2,963 2,660 Non-controlling interest 11 12 Preferred equity 362 362 Enable partners’ equity 7,198 7,280 Reconciliation of Investment in Enable: CenterPoint Energy’s and CERC’s ownership interest in Enable partners’ equity $ 3,887 $ 3,935 CenterPoint Energy’s and CERC’s basis difference (1,436 ) (1,463 ) CenterPoint Energy’s and CERC’s equity method investment in Enable $ 2,451 $ 2,472

Goodwill and Other Intangibles

Goodwill and Other Intangibles (CenterPoint Energy and CERC)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles (CenterPoint Energy and CERC) [Text Block]	Goodwill and Other Intangibles (CenterPoint Energy and CERC) CenterPoint Energy’s and CERC’s goodwill by reportable business segment as of both June 30, 2018 and December 31, 2017 is as follows: (in millions) Natural Gas Distribution $ 746 Energy Services (1) 110 Other Operations 11 Total $ 867 (1) Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012. The tables below present information on CenterPoint Energy’s and CERC’s other intangible assets recorded in Other non-current assets on the Condensed Consolidated Balance Sheets. June 30, 2018 December 31, 2017 Useful Lives Gross Carrying Amount Accumulated Amortization Net Balance Gross Carrying Amount Accumulated Amortization Net Balance (in years) (in millions) Customer relationships 15 $ 86 $ (25 ) $ 61 $ 86 $ (21 ) $ 65 Covenants not to compete 4 4 (2 ) 2 4 (2 ) 2 Other Various 15 (9 ) 6 15 (8 ) 7 Total $ 105 $ (36 ) $ 69 $ 105 $ (31 ) $ 74 Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Amortization expense of intangible assets $ 2 $ 1 $ 5 $ 3

Indexed Debt Securities (ZENS)

Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy)	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) [Text Block]	Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) (a) Investment in Securities Related to ZENS In 1995, CenterPoint Energy sold a cable television subsidiary to TW and received certain TW securities as partial consideration. A subsidiary of CenterPoint Energy holds shares of certain securities detailed in the table below, which are classified as trading securities and are expected to be held to facilitate CenterPoint Energy’s ability to meet its obligation under the ZENS. Unrealized gains and losses resulting from changes in the market value of the ZENS-Related Securities are recorded in CenterPoint Energy’s Condensed Statements of Consolidated Income. Shares Held June 30, 2018 December 31, 2017 AT&T Common 10,212,945 — Charter Common 872,503 872,503 Time Common — 888,392 TW Common — 7,107,130 (b) ZENS In September 1999, CenterPoint Energy issued ZENS having an original principal amount of $1 billion of which $828 million remain outstanding as of June 30, 2018 . Each ZENS was originally exchangeable at the holder’s option at any time for an amount of cash equal to 95% of the market value of the reference shares of TW Common attributable to such note. The number and identity of the reference shares attributable to each ZENS are adjusted for certain corporate events. On October 22, 2016, AT&T announced that it had entered into a definitive agreement to acquire TW in a stock and cash transaction. On February 15, 2017, TW shareholders approved the announced transaction with AT&T. The merger closed on June 14, 2018. CenterPoint Energy received $53.75 and 1.437 shares of AT&T Common for each share of TW Common held, resulting in cash proceeds of $382 million and 10,212,945 shares of AT&T Common. In accordance with the terms of the ZENS, CenterPoint Energy remitted $382 million to ZENS note holders in July 2018, which reduced the contingent principal amount. On November 26, 2017, Meredith announced that it had entered into a definitive merger agreement with Time. Pursuant to the merger agreement, upon closing of the merger, a subsidiary of Meredith would purchase for cash all outstanding Time Common shares for $18.50 per share. The transaction was consummated on January 31, 2018. CenterPoint Energy elected to make a reference share offer adjustment and distribute additional interest, if any, in accordance with the terms of its ZENS rather than electing to increase the early exchange ratio to 100% . CenterPoint Energy’s distribution of additional interest in connection with the reference share offer was proportionate to the percentage of eligible shares that were validly tendered by Time stockholders in Meredith’s tender offer. CenterPoint Energy received $18.50 for each share of Time Common held, resulting in cash proceeds of approximately $16 million . In accordance with the terms of the ZENS, CenterPoint Energy distributed additional interest of approximately $16 million to ZENS holders on March 6, 2018, which reduced the contingent principal amount. As a result, CenterPoint Energy recorded the following during the six months ended June 30, 2018 : Meredith/Time AT&T/TW (in millions) (in millions) Cash payment to ZENS note holders $ 16 Due to ZENS note holders (1) $ 382 Indexed debt – reduction (4 ) Indexed debt – reduction (95 ) Indexed debt securities derivative – reduction (1 ) Indexed debt securities derivative – reduction (45 ) Loss on indexed debt securities $ 11 Loss on indexed debt securities $ 242 (1) Cash of approximately $382 million was paid to ZENS note holders in July 2018. CenterPoint Energy’s reference shares for each ZENS consisted of the following: June 30, 2018 December 31, 2017 (in shares) AT&T Common 0.7185 — Charter Common 0.061382 0.061382 Time Common — 0.0625 TW Common — 0.5 As of June 30, 2018 , the contingent principal amount of the ZENS was $484 million .

Short-Term Borrowings and Long-

Short-Term Borrowings and Long-term Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Short-term Borrowings and Long-term Debt [Text Block]	Short-term Borrowings and Long-term Debt (a) Short-term Borrowings (CenterPoint Energy and CERC) Inventory Financing . NGD has AMAs associated with its utility distribution service in Arkansas, Louisiana, Mississippi, Oklahoma and Texas. In March 2018, NGD’s third party AMAs in Arkansas, Louisiana and Oklahoma expired, and NGD entered into new AMAs with CES effective April 1, 2018 in these states. The AMAs have varying terms, the longest of which expires in 2021. Pursuant to the provisions of the agreements, NGD sells natural gas and agrees to repurchase an equivalent amount of natural gas during the winter heating seasons at the same cost, plus a financing charge. These transactions are accounted for as an inventory financing and had an associated principal obligation of $ -0- and $39 million as of June 30, 2018 and December 31, 2017 , respectively. (b) Long-term Debt Debt Issuances. During the six months ended June 30, 2018 , the following debt instruments were issued: Issuance Date Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) Houston Electric February 2018 General mortgage bonds $ 400 3.95% 2048 CERC Corp. March 2018 Unsecured senior notes 300 3.55% 2023 CERC Corp. March 2018 Unsecured senior notes 300 4.00% 2028 The proceeds from these issuances were used for general limited liability company and corporate purposes, as applicable, including to repay portions of outstanding commercial paper and borrowings under CenterPoint Energy’s money pool. Credit Facility . In May 2018, CenterPoint Energy entered into an amendment to its revolving credit facility that will increase the aggregate commitments from $1.7 billion to $3.3 billion effective the earlier of (i) the termination of all commitments by certain lenders to provide the Bridge Facility and (ii) the payment in full of all obligations (other than contingent obligations) under the Bridge Facility and termination of all commitments to advance additional credit thereunder, and in each case, so long as the Merger Agreement has not been terminated pursuant to the terms thereof without consummation of the Merger. This increase to CenterPoint Energy’s revolving credit facility will automatically expire on the earlier of the (a) termination date of the revolving credit facility and (b) if the Merger Agreement is terminated without consummation of the Merger, the date that is 90 days after such termination. In addition, the amendment provides for a temporary increase on the maximum ratio of debt for borrowed money to capital from 65% to 75% until the earlier of (i) June 30, 2019 and (ii) the termination of all commitments in respect of the Bridge Facility without any borrowing thereunder. The Registrants had the following revolving credit facilities and utilization of such facilities: June 30, 2018 December 31, 2017 Size of Loans Letters Commercial Weighted Average Interest Rate Loans Letters Commercial Weighted Average Interest Rate (in millions, except weighted average interest rate) CenterPoint Energy $ 1,700 (1) $ — $ 6 $ — — % $ — $ 6 $ 855 1.88 % Houston Electric 300 — 4 — — — 4 — — CERC Corp. 900 — 1 565 2.37 % — 1 898 1.72 % Total $ 2,900 $ — $ 11 $ 565 $ — $ 11 $ 1,753 (1) Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility will increase to $3.3 billion upon the satisfaction of certain conditions described above. Execution Date Company Size of Facility Draw Rate of LIBOR plus (1) Financial Covenant Limit on Debt for Borrowed Money to Capital Ratio Debt for Borrowed Money to Capital Ratio as of June 30, 2018 (2) Termination Date (in millions) March 3, 2016 CenterPoint Energy $ 1,700 (3) 1.250% 75% (4) (5) 52.1% March 3, 2022 March 3, 2016 Houston Electric 300 1.125% 65% (5) 50.7% March 3, 2022 March 3, 2016 CERC Corp. 900 1.250% 65% 37.8% March 3, 2022 (1) Based on current credit ratings. (2) As defined in the revolving credit facility agreement, excluding Securitization Bonds. (3) Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility will increase to $3.3 billion upon the satisfaction of certain conditions described above. (4) CenterPoint Energy’s financial covenant limit will return to 65% upon the earlier of (i) June 30, 2019 or (ii) the termination of all commitments in respect of the Bridge Facility without any borrowing thereunder. (5) For CenterPoint Energy (whenever its financial covenant limit is 65% ) and Houston Electric, the financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive 12 -month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date CenterPoint Energy delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of CenterPoint Energy’s certification or (iii) the revocation of such certification. The Registrants were in compliance with all financial debt covenants as of June 30, 2018 . Other. As of both June 30, 2018 and December 31, 2017 , Houston Electric had issued $118 million of general mortgage bonds as collateral for long-term debt of CenterPoint Energy. These bonds are not reflected in Houston Electric’s consolidated financial statements because of the contingent nature of the obligations.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes [Text Block]	Income Taxes The Registrants reported the following effective tax rates: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 CenterPoint Energy 15 % 36 % 27 % 36 % Houston Electric 21 % 36 % 22 % 36 % CERC 22 % 35 % 22 % 37 % CenterPoint Energy’s lower effective tax rate for the three and six months ended June 30, 2018 compared to the same periods for 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA, and partially offset by the impact of state tax law changes which resulted in re-measurement of state deferred taxes. The state tax law changes combined with the lower earnings for the period result in the lower than expected effective tax rate for the current quarter and higher than expected six-month effective tax rate. Houston Electric’s and CERC’s lower effective tax rate for the three and six months ended June 30, 2018 compared to the same periods for 2017 was primarily due to the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018 as prescribed by the TCJA. The Registrants reported no uncertain tax liability as of June 30, 2018 and expect no significant changes to the uncertain tax liability over the next twelve months. Tax years through 2016 have been audited and settled with the IRS. For the 2017 and 2018 tax years, CenterPoint Energy is a participant in the IRS’s Compliance Assurance Process.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies [Text Block]	Commitments and Contingencies (a) Natural Gas Supply Commitments (CenterPoint Energy and CERC) Natural gas supply commitments include natural gas contracts related to CenterPoint Energy’s and CERC’s Natural Gas Distribution and Energy Services business segments, which have various quantity requirements and durations, that are not classified as non-trading derivative assets and liabilities in CenterPoint Energy’s and CERC’s Condensed Consolidated Balance Sheets as of June 30, 2018 and December 31, 2017 as these contracts meet an exception as “normal purchases contracts” or do not meet the definition of a derivative. Natural gas supply commitments also include natural gas transportation contracts that do not meet the definition of a derivative. As of June 30, 2018 , minimum payment obligations for natural gas supply commitments are approximately: (in millions) Remaining six months of 2018 $ 185 2019 264 2020 168 2021 82 2022 51 2023 and beyond 123 (b) Legal, Environmental and Other Matters Legal Matters Gas Market Manipulation Cases. CenterPoint Energy, Houston Electric or their predecessor, Reliant Energy, and certain of their former subsidiaries have been named as defendants in certain lawsuits described below. Under a master separation agreement between CenterPoint Energy and a former subsidiary, RRI, CenterPoint Energy and its subsidiaries are entitled to be indemnified by RRI and its successors for any losses, including certain attorneys’ fees and other costs, arising out of these lawsuits. In May 2009, RRI sold its Texas retail business to a subsidiary of NRG and RRI changed its name to RRI Energy, Inc. In December 2010, Mirant Corporation merged with and became a wholly-owned subsidiary of RRI, and RRI changed its name to GenOn. In December 2012, NRG acquired GenOn through a merger in which GenOn became a wholly-owned subsidiary of NRG. None of the sale of the retail business, the merger with Mirant Corporation, or the acquisition of GenOn by NRG alters RRI’s (now GenOn’s) contractual obligations to indemnify CenterPoint Energy and its subsidiaries, including Houston Electric, for certain liabilities, including their indemnification obligations regarding the gas market manipulation litigation. A large number of lawsuits were filed against numerous gas market participants in a number of federal and western state courts in connection with the operation of the natural gas markets in 2000–2002. CenterPoint Energy and its affiliates have since been released or dismissed from all such cases. CES, a subsidiary of CERC Corp., was a defendant in a case now pending in federal court in Nevada alleging a conspiracy to inflate Wisconsin natural gas prices in 2000–2002. On May 24, 2016, the district court granted CES’s motion for summary judgment, dismissing CES from the case. The plaintiffs have appealed that ruling. CenterPoint Energy and CES intend to continue vigorously defending against the plaintiffs’ claims. In June 2017, GenOn and various affiliates filed for protection under Chapter 11 of the U.S. Bankruptcy Code. In December 2017, GenOn received court approval of a restructuring plan and is expected to emerge from Chapter 11 in 2018. CenterPoint Energy, CERC, and CES submitted proofs of claim in the bankruptcy proceedings to protect their indemnity rights. If GenOn were unable to meet its indemnity obligations or satisfy a liability that has been assumed in the gas market manipulation litigation, then CenterPoint Energy, Houston Electric or CERC could incur liability and be responsible for satisfying the liability. CenterPoint Energy does not expect the ultimate outcome of the case against CES to have a material adverse effect on its financial condition, results of operations or cash flows. Minnehaha Academy (CenterPoint Energy and CERC). On August 2, 2017, a natural gas explosion occurred at the Minnehaha Academy in Minneapolis, Minnesota, resulting in the deaths of two school employees, serious injuries to others and significant property damage to the school. CenterPoint Energy, certain of its subsidiaries, including CERC, and the contractor company working in the school have been named in litigation arising out of this incident. CenterPoint Energy has reached confidential settlement agreements with some claimants. Additionally, CenterPoint Energy is cooperating with the ongoing investigation conducted by the National Transportation Safety Board. Further, CenterPoint Energy is contesting approximately $200,000 in fines imposed by the Minnesota Office of Pipeline Safety. In early 2018, the Minnesota Occupational Safety and Health Administration concluded its investigation without any adverse findings against CenterPoint Energy. CenterPoint Energy’s general and excess liability insurance policies provide coverage for third party bodily injury and property damage claims. Environmental Matters MGP Sites (CenterPoint Energy and CERC). CERC and its predecessors operated MGPs in the past. With respect to certain Minnesota MGP sites, CERC has completed state-ordered remediation and continues state-ordered monitoring and water treatment. As of June 30, 2018 , CERC had a recorded liability of $7 million for continued monitoring and any future remediation required by regulators in Minnesota. The estimated range of possible remediation costs for the sites for which CERC believes it may have responsibility was $4 million to $30 million based on remediation continuing for 30 to 50 years. The cost estimates are based on studies of a site or industry average costs for remediation of sites of similar size. The actual remediation costs will depend on the number of sites to be remediated, the participation of other PRPs, if any, and the remediation methods used. In addition to the Minnesota sites, the EPA and other regulators have investigated MGP sites that were owned or operated by CERC or may have been owned by one of its former affiliates. CenterPoint Energy and CERC do not expect the ultimate outcome of these matters to have a material adverse effect on the financial condition, results of operations or cash flows of either CenterPoint Energy or CERC. Asbestos. Some facilities owned by the Registrants or their predecessors in interest contain or have contained asbestos insulation and other asbestos-containing materials. The Registrants are from time to time named, along with numerous others, as defendants in lawsuits filed by a number of individuals who claim injury due to exposure to asbestos, and the Registrants anticipate that additional claims may be asserted in the future. Although their ultimate outcome cannot be predicted at this time, the Registrants do not expect these matters, either individually or in the aggregate, to have a material adverse effect on their financial condition, results of operations or cash flows. Other Environmental. From time to time, the Registrants identify the presence of environmental contaminants during operations or on property where predecessor companies have conducted operations. Other such sites involving contaminants may be identified in the future. The Registrants have and expect to continue to remediate any identified sites consistent with state and federal legal obligations. From time to time, the Registrants have received notices, and may receive notices in the future, from regulatory authorities or others regarding status as a PRP in connection with sites found to require remediation due to the presence of environmental contaminants. In addition, the Registrants have been, or may be, named from time to time as defendants in litigation related to such sites. Although the ultimate outcome of such matters cannot be predicted at this time, the Registrants do not expect these matters, either individually or in the aggregate, to have a material adverse effect on their financial condition, results of operations or cash flows. Other Proceedings The Registrants are involved in other legal, environmental, tax and regulatory proceedings before various courts, regulatory commissions and governmental agencies regarding matters arising in the ordinary course of business. From time to time, the Registrants are also defendants in legal proceedings with respect to claims brought by various plaintiffs against broad groups of participants in the energy industry. Some of these proceedings involve substantial amounts. The Registrants regularly analyze current information and, as necessary, provide accruals for probable and reasonably estimable liabilities on the eventual disposition of these matters. The Registrants do not expect the disposition of these matters to have a material adverse effect on the Registrants’ financial condition, results of operations or cash flows.

Earnings Per Share (CenterPoint

Earnings Per Share (CenterPoint Energy)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share (CenterPoint Energy) [Text Block]	Earnings Per Share (CenterPoint Energy) The following table reconciles numerators and denominators of CenterPoint Energy’s basic and diluted earnings (loss) per share calculations: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions, except share and per share amounts) Net income (loss) $ (75 ) $ 135 $ 90 $ 327 Basic weighted average shares outstanding 431,523,000 430,996,000 431,378,000 430,896,000 Plus: Incremental shares from assumed conversions: Restricted stock (1) — 2,801,000 3,029,000 2,801,000 Diluted weighted average shares 431,523,000 433,797,000 434,407,000 433,697,000 Basic earnings (loss) per share Net income (loss) $ (0.17 ) $ 0.31 $ 0.21 $ 0.76 Diluted earnings (loss) per share Net income (loss) $ (0.17 ) $ 0.31 $ 0.21 $ 0.75 (1) 3,029,000 incremental shares from assumed conversions of restricted stock have not been included in the computation of diluted earnings (loss) per share for the three months ended June 30, 2018 as their inclusion would be anti-dilutive.

Reportable Business Segments

Reportable Business Segments	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Reportable Business Segments [Text Block]	Reportable Business Segments The Registrants’ determination of reportable business segments considers the strategic operating units under which the Registrants manage sales, allocate resources and assess performance of various products and services to wholesale or retail customers in differing regulatory environments. The Registrants use operating income as the measure of profit or loss for the business segments other than Midstream Investments, where equity in earnings is used. Reportable business segments by Registrant are as follows: Electric Transmission & Distribution Natural Gas Distribution Energy Services Midstream Investments Other Operations CenterPoint Energy X X X X X Houston Electric X CERC X X X X Electric Transmission & Distribution consists of the electric transmission and distribution function. Natural Gas Distribution consists of intrastate natural gas sales to, and natural gas transportation and distribution for, residential, commercial, industrial and institutional customers. Energy Services consists of non-rate regulated natural gas sales and services operations. Midstream Investments consists of the equity investment in Enable (excluding the Series A Preferred Units). Other Operations consists primarily of other corporate operations which support all of the business operations. Houston Electric consists of a single reportable business segment and therefore is not included in the tabular business segment presentation below. Operating income (loss) amounts for 2017 have been recast to reflect the adoption of ASU 2017-07 (see Note 2 for further information). Financial data for business segments is as follows: CenterPoint Energy Three Months Ended June 30, 2018 2017 Revenues from Net Operating (Loss) Revenues from Net Operating (in millions) Electric Transmission & Distribution $ 854 (1) $ — $ 181 $ 752 (1) $ — $ 171 Natural Gas Distribution 487 8 7 470 7 42 Energy Services 841 19 15 918 13 16 Midstream Investments (2) — — — — — — Other Operations 4 — (16 ) 3 — 11 Eliminations — (27 ) — — (20 ) — Consolidated $ 2,186 $ — $ 187 $ 2,143 $ — $ 240 Six Months Ended June 30, 2018 2017 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Revenues from External Customers Net Intersegment Revenues Operating (in millions) Electric Transmission & Distribution $ 1,605 (1) $ — $ 296 $ 1,391 (1) $ — $ 257 Natural Gas Distribution 1,630 18 163 1,377 16 210 Energy Services 2,098 47 (11 ) 2,103 24 51 Midstream Investments (2) — — — — — — Other Operations 8 — (10 ) 7 — 13 Eliminations — (65 ) — — (40 ) — Consolidated $ 5,341 $ — $ 438 $ 4,878 $ — $ 531 (1) CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Affiliates of NRG $ 169 $ 167 $ 330 $ 319 Affiliates of Vistra Energy Corp. 59 53 113 100 CERC Three Months Ended June 30, 2018 2017 Revenues from Net Operating Revenues from Net Operating (in millions) Natural Gas Distribution $ 487 $ 8 $ 7 $ 470 $ 7 $ 42 Energy Services 841 19 15 918 13 16 Midstream Investments (2) — — — — — — Other Operations — — — (1 ) — 1 Eliminations — (27 ) — — (20 ) — Consolidated $ 1,328 $ — $ 22 $ 1,387 $ — $ 59 Six Months Ended June 30, 2018 2017 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) (in millions) Natural Gas Distribution $ 1,630 $ 18 $ 163 $ 1,377 $ 16 $ 210 Energy Services 2,098 47 (11 ) 2,103 24 51 Midstream Investments (2) — — — — — — Other Operations — — 1 — — (3 ) Eliminations — (65 ) — — (40 ) — Consolidated $ 3,728 $ — $ 153 $ 3,480 $ — $ 258 (2) CenterPoint Energy’s and CERC’s Midstream Investments’ equity earnings, net are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Enable $ 58 $ 59 $ 127 $ 131 CenterPoint Energy and CERC Total Assets June 30, 2018 December 31, 2017 CenterPoint Energy CERC CenterPoint CERC (in millions) Electric Transmission & Distribution $ 10,430 $ — $ 10,292 $ — Natural Gas Distribution 6,501 6,501 6,608 6,608 Energy Services 1,256 1,256 1,521 1,521 Midstream Investments 2,451 2,451 2,472 2,472 Other Operations 2,311 (3) 89 2,497 (3) 70 Eliminations (841 ) (655 ) (654 ) (559 ) Consolidated $ 22,108 $ 9,642 $ 22,736 $ 10,112 (3) Includes pension and other postemployment-related regulatory assets of $577 million and $600 million , respectively, as of June 30, 2018 and December 31, 2017 .

Supplemental Disclosure of Cash

Supplemental Disclosure of Cash Flow Information	6 Months Ended
	Jun. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosure of Cash Flow Information [Text Block]	Supplemental Disclosure of Cash Flow Information The table below provides supplemental disclosure of cash flow information: Six Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Cash Payments/Receipts: Interest, net of capitalized interest $ 167 $ 90 $ 50 $ 182 $ 94 $ 56 Income taxes, net 88 120 3 11 76 3 Non-cash transactions: Accounts payable related to capital expenditures 133 75 69 106 75 44 The table below provides a reconciliation of cash, cash equivalents and restricted cash reported in the Condensed Consolidated Balance Sheets to the amount reported in the Condensed Statements of Consolidated Cash Flows: June 30, 2018 December 31, 2017 CenterPoint Energy Houston Electric CenterPoint Energy Houston Electric (in millions) Cash and cash equivalents $ 328 $ 253 $ 260 $ 238 Restricted cash included in Prepaid expenses and other current assets 37 37 35 35 Restricted cash included in Other 1 1 1 1 Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows $ 366 $ 291 $ 296 $ 274 CERC does not have restricted cash and therefore was not included in the table above.

Related Party Transactions (Hou

Related Party Transactions (Houston Electric and CERC)	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions (Houston Electric and CERC) [Text Block]	Related Party Transactions (Houston Electric and CERC) Houston Electric and CERC participate in a money pool through which they can borrow or invest on a short-term basis. Funding needs are aggregated and external borrowing or investing is based on the net cash position. The net funding requirements of the money pool are expected to be met with borrowings under CenterPoint Energy’s revolving credit facility or the sale of CenterPoint Energy’s commercial paper. The table below summarizes money pool activity: June 30, 2018 December 31, 2017 Houston Electric CERC Houston Electric CERC (in millions) Money pool investments (borrowings) (1) $ 26 $ — $ (60 ) $ (570 ) Weighted average interest rate 2.00 % — % 1.90 % 1.90 % (1) Included in Accounts and notes receivable (payable)–affiliated companies in the Condensed Consolidated Balance Sheets. Affiliate related net interest income (expense) was not material for either the three or six months ended June 30, 2018 or 2017 . CenterPoint Energy provides some corporate services to Houston Electric and CERC. The costs of services have been charged directly to Houston Electric and CERC using methods that management believes are reasonable. These methods include negotiated usage rates, dedicated asset assignment and proportionate corporate formulas based on operating expenses, assets, gross margin, employees and a composite of assets, gross margin and employees. Houston Electric provides a number of services to CERC. These services are billed at actual cost, either directly or as an allocation and include fleet services, shop services, geographic services, surveying and right-of-way services, radio communications, data circuit management and field operations. Additionally, CERC provides certain services to Houston Electric. These services are billed at actual cost, either directly or as an allocation and include line locating and other miscellaneous services. These charges are not necessarily indicative of what would have been incurred had Houston Electric and CERC not been affiliates. Amounts charged for these services were as follows and are included primarily in operation and maintenance expenses: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Corporate service charges $ 47 $ 35 $ 44 $ 32 $ 91 $ 69 $ 86 $ 63 Net affiliate service charges (billings) (3 ) 3 (4 ) 4 (5 ) 5 (5 ) 5 Houston Electric and CERC paid dividends on their common shares and stock, respectively, to Utility Holding, LLC as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Dividends paid $ 31 $ 125 $ 10 $ 140 $ 63 $ 211 $ 42 $ 248

Subsequent Events (CenterPoint

Subsequent Events (CenterPoint Energy and CERC)	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
Subsequent Events (CenterPoint Energy and CERC) [Text Block]	Subsequent Events (CenterPoint Energy and CERC) CenterPoint Energy Dividend Declaration On July 26, 2018 , CenterPoint Energy’s Board of Directors declared a regular quarterly cash dividend of $0.2775 per share of common stock payable on September 13, 2018 to shareholders of record as of the close of business on August 16, 2018 . Enable Distributions Declarations On August 1, 2018 , Enable declared a quarterly cash distribution of $0.318 per unit on all of its outstanding common units for the quarter ended June 30, 2018 . Accordingly, CERC Corp. expects to receive a cash distribution of approximately $74 million from Enable in the third quarter of 2018 to be made with respect to CERC Corp.’s investment in common units of Enable for the second quarter of 2018. On August 1, 2018 , Enable declared a quarterly cash distribution of $0.625 per Series A Preferred Unit for the quarter ended June 30, 2018 . Accordingly, CenterPoint Energy expects to receive a cash distribution of approximately $9 million from Enable in the third quarter of 2018 to be made with respect to CenterPoint Energy’s investment in Series A Preferred Units of Enable for the second quarter of 2018.

New Accounting Pronouncements (

New Accounting Pronouncements (Tables)	6 Months Ended
	Jun. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	The following table provides an overview of recently adopted or issued accounting pronouncements applicable to all the Registrants, unless otherwise noted. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2014-09- Revenue from Contracts with Customers (Topic 606) and related amendments This standard provides a comprehensive new revenue recognition model that requires revenue to be recognized in a manner that depicts the transfer of goods or services to a customer at an amount that reflects the consideration expected to be received in exchange for those goods or services. Transition method: modified retrospective January 1, 2018 Note 4 addresses the disclosure requirements. Adoption of the standard did not result in significant changes to revenue recognition. A substantial amount of the Registrants’ revenues are tariff and/or derivative based, which were not significantly impacted by these ASUs. ASU 2017-05- Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets This standard clarifies when and how to apply ASC 610-20, which was issued as part of ASU 2014-09. It amends or supersedes the guidance in ASC 350 and ASC 360 on determining a gain or loss recognized upon the derecognition of nonfinancial assets. Transition method: modified retrospective January 1, 2018 ASU 2017-05 eliminates industry specific guidance, including ASC 360-20 Property, Plant, and Equipment - Real Estate Sales, for the recognition of gains or losses upon the sale of in-substance real estate. CenterPoint Energy and CERC elected to apply the practical expedient upon adoption to only evaluate transactions that were not determined to be complete as of the date of adoption. Subsequent to adoption, gains or losses on sales or dilution events in CenterPoint Energy’s or CERC’s investment in Enable may result in gains or losses recognized in earnings. See Note 9 for further discussion. ASU 2016-01-Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ASU 2018-03-Technical Corrections and Improvements to Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This standard requires equity investments that do not result in consolidation and are not accounted for under the equity method to be measured at fair value and to recognize any changes in fair value in net income unless the investments qualify for the new practicability exception. It does not change the guidance for classifying and measuring investments in debt securities and loans. It also changes certain disclosure requirements and other aspects related to recognition and measurement of financial assets and financial liabilities. Transition method: cumulative-effect adjustment to beginning retained earnings, and two features prospective January 1, 2018 The adoption of this standard did not have an impact on the Registrants’ financial position, results of operations or cash flows. The Registrants elected the practicability exception for investments without a readily determinable fair value to be measured at cost. This includes the Series A Preferred Units in Enable, which were previously accounted for under the cost method. See Note 9 for further discussion. ASU 2016-15- Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments This standard provides clarifying guidance on the classification of certain cash receipts and payments in the statement of cash flows and eliminates the variation in practice related to such classifications. Transition method: retrospective January 1, 2018 The adoption did not have a material impact on the Registrants’ financial position, results of operations or disclosures. However, CenterPoint Energy’s and Houston Electric’s Condensed Statements of Consolidated Cash Flows reflect an increase in investing activities and a corresponding decrease in operating activities of $1 million and $3 million for the six months ended June 30, 2018 and 2017, respectively, due to the requirement that cash proceeds from COLI policies be classified as cash inflows from investing activity. ASU 2016-18- Statement of Cash Flows (Topic 230): Restricted Cash This standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. As a result, the statement of cash flows will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. Transition method: retrospective January 1, 2018 The adoption of this standard did not have an impact on the Registrants’ financial position, results of operations or disclosures. However, CenterPoint Energy’s and Houston Electric’s Condensed Statements of Consolidated Cash Flows are reconciled to cash, cash equivalents and restricted cash, resulting in a decrease in investing activities of $2 million and an increase in investing activities of $8 million for the six months ended June 30, 2018 and 2017, respectively. Recently Adopted Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2017-01- Business Combinations (Topic 805): Clarifying the Definition of a Business This standard revises the definition of a business. If substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, then under ASU 2017-01, the asset or group of assets is not a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs to be more closely aligned with how outputs are described in ASC 606. Transition method: prospective January 1, 2018 The adoption of this revised definition will reduce the number of transactions that are accounted for as a business combination, and therefore may have a potential impact on the Registrants’ accounting for future acquisitions. ASU 2017-04- Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This standard eliminates Step 2 of the goodwill impairment test, which required a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s and CERC’s future calculation of goodwill impairments if an impairment is identified. ASU 2017-07- Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This standard requires an employer to report the service cost component of the net periodic pension cost and postretirement benefit cost in the same line item(s) as other employee compensation costs arising from services rendered during the period; all other components will be presented separately from the line item(s) that includes the service cost and outside of any subtotal of operating income. In addition, only the service cost component will be eligible for capitalization in assets. Transition method: retrospective for the presentation of the service cost component and other components; prospective for the capitalization of the service cost component January 1, 2018 The adoption of this standard did not have a material impact on the Registrants’ financial position, results of operations, cash flows or disclosures; however, it resulted in the increases to operating income and corresponding decreases to other income reported in the table below. Other components previously capitalized in assets will be recorded as regulatory assets in the Registrants’ rate-regulated businesses, prospectively. ASU 2017-09- Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting This standard clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as a modification. Entities will apply the modification accounting guidance if the value, vesting conditions or classification of the award changes. Transition method: prospective January 1, 2018 The adoption of this standard will have an impact on CenterPoint Energy’s accounting for future changes to share-based payment awards. The table below reflects the impact of adoption of ASU 2017-07: Three Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 15 $ 8 $ 4 $ 17 $ 7 $ 6 Decrease to other income 15 8 4 17 7 6 Six Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Increase to operating income $ 29 $ 15 $ 8 $ 34 $ 15 $ 11 Decrease to other income 29 15 8 34 15 11 Issued, Not Yet Effective Accounting Standards ASU Number and Name Description Date of Adoption Financial Statement Impact upon Adoption ASU 2016-02- Leases (Topic 842) and related amendments ASU 2018-01- Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842 ASU 2016-02 provides a comprehensive new lease model that requires lessees to recognize assets and liabilities for most leases and would change certain aspects of lessor accounting. Transition method : modified retrospective ASU 2018-01 allows entities to elect not to assess whether existing land easements that were not previously accounted for in accordance with ASC 840 Leases under ASC 842 Leases when transitioning to the new leasing standard. January 1, 2019 Early adoption is permitted The Registrants will elect the practical expedient on existing easements provided by ASU 2018-01 and are evaluating other available transitional practical expedients. The Registrants are in the process of reviewing contracts to identify leases as defined in ASU 2016-02 and expect to recognize on the statements of financial position right-of-use assets and lease liabilities for the majority of their respective leases that are currently classified as operating leases. The Registrants are continuing to assess the impact that adoption of these standards will have on their financial position, results of operations, cash flows and disclosures. ASU 2017-12- Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities This standard expands an entity’s ability to hedge nonfinancial and financial risk components and reduce complexity in fair value hedges of interest rate risk. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness, eases certain documentation and assessment requirements and updates the presentation and disclosure requirements. Transition method: cumulative-effect adjustment for elimination of the separate measurement of ineffectiveness; prospective for presentation and disclosure January 1, 2019 Early adoption is permitted The Registrants are currently assessing the impact that adoption of this standard will have on their financial position, results of operations, cash flows and disclosures. ASU 2018-02-Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA and requires entities to provide certain disclosures regarding stranded tax effects. Transition method: either in the period of adoption or retrospective January 1, 2019 Early adoption is permitted The adoption of this standard will allow the Registrants to reclass stranded deferred tax adjustments primarily related to benefit plans from other comprehensive income to retained earnings. The Registrants are currently assessing the impact that adoption of this standard will have on their financial position and disclosures.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table Text Block]	The following tables disaggregate revenues by reportable business segment and major source: CenterPoint Energy Three Months Ended June 30, 2018 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 860 $ 509 $ 78 $ 2 $ 1,449 $ 758 $ 463 $ 116 $ 1 $ 1,338 Derivatives income — — 782 — 782 — — 815 — 815 Other (3) (6 ) (14 ) — 2 (18 ) (6 ) 14 — 2 10 Eliminations — (8 ) (19 ) — (27 ) — (7 ) (13 ) — (20 ) Total revenues $ 854 $ 487 $ 841 $ 4 $ 2,186 $ 752 $ 470 $ 918 $ 3 $ 2,143 Six Months Ended June 30, 2018 2017 Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Electric Transmission & Distribution (1) Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 1,621 $ 1,695 $ 256 $ 3 $ 3,575 $ 1,402 $ 1,388 $ 258 $ 2 $ 3,050 Derivatives income (4 ) — 1,889 — 1,885 1 — 1,869 — 1,870 Other (3) (12 ) (47 ) — 5 (54 ) (12 ) 5 — 5 (2 ) Eliminations — (18 ) (47 ) — (65 ) — (16 ) (24 ) — (40 ) Total revenues $ 1,605 $ 1,630 $ 2,098 $ 8 $ 5,341 $ 1,391 $ 1,377 $ 2,103 $ 7 $ 4,878 Houston Electric Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Revenue from contracts $ 860 $ 758 $ 1,621 $ 1,402 Other (3) (6 ) (6 ) (12 ) (12 ) $ 854 $ 752 $ 1,609 $ 1,390 CERC Three Months Ended June 30, 2018 2017 Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 509 $ 78 $ — $ 587 $ 463 $ 116 $ — $ 579 Derivatives income — 782 — 782 — 815 — 815 Other (3) (14 ) — — (14 ) 14 — (1 ) 13 Eliminations (8 ) (19 ) — (27 ) (7 ) (13 ) — (20 ) Total revenues $ 487 $ 841 $ — $ 1,328 $ 470 $ 918 $ (1 ) $ 1,387 Six Months Ended June 30, 2018 2017 Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total Natural Gas Distribution (1) Energy Services (2) Other Operations (2) Total (in millions) Revenue from contracts $ 1,695 $ 256 $ — $ 1,951 $ 1,388 $ 258 $ — $ 1,646 Derivatives income — 1,889 — 1,889 — 1,869 — 1,869 Other (3) (47 ) — — (47 ) 5 — — 5 Eliminations (18 ) (47 ) — (65 ) (16 ) (24 ) — (40 ) Total revenues $ 1,630 $ 2,098 $ — $ 3,728 $ 1,377 $ 2,103 $ — $ 3,480 (1) Reflected in Utility revenues in the Condensed Statements of Consolidated Income. (2) Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income. (3) Primarily consists of income from ARPs and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. The Registrants recognize ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2018
Retirement Benefits [Abstract]
Schedule of Defined Benefit Plans Disclosures [Table Text Block]	The table below reflects the expected contributions to be made to the pension plans and postretirement benefit plan during 2018: CenterPoint Energy Houston Electric CERC (in millions) Expected minimum contribution to pension plans during 2018 $ 67 $ — $ — Expected contribution to postretirement benefit plan in 2018 16 10 5 The table below reflects the contributions made to the pension plans and postretirement benefit plan during 2018: Three Months Ended June 30, 2018 Six Months Ended June 30, 2018 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Pension plans $ 2 $ — $ — $ 64 $ — $ — Postretirement benefit plan 3 2 1 7 4 2 The Registrants’ net periodic cost, before considering amounts subject to overhead allocations for capital expenditure projects or for amounts subject to deferral for regulatory purposes, includes the following components relating to pension and postretirement benefits: Pension Benefits (CenterPoint Energy) Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Service cost (1) $ 9 $ 9 $ 18 $ 18 Interest cost (2) 19 22 39 44 Expected return on plan assets (2) (26 ) (24 ) (53 ) (48 ) Amortization of prior service cost (2) 2 3 4 5 Amortization of net loss (2) 11 15 22 29 Net periodic cost $ 15 $ 25 $ 30 $ 48 Postretirement Benefits Three Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ 1 $ — $ — $ 1 $ — $ — Interest cost (2) 4 2 1 4 2 1 Expected return on plan assets (2) (2 ) (1 ) (1 ) (2 ) (1 ) — Amortization of prior service cost (credit) (2) (1 ) (2 ) 1 (1 ) (1 ) 1 Net periodic cost $ 2 $ (1 ) $ 1 $ 2 $ — $ 2 Six Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Service cost (1) $ 1 $ — $ — $ 1 $ — $ — Interest cost (2) 7 4 2 8 4 2 Expected return on plan assets (2) (3 ) (2 ) (1 ) (3 ) (2 ) — Amortization of prior service cost (credit) (2) (2 ) (3 ) 1 (2 ) (2 ) 1 Net periodic cost $ 3 $ (1 ) $ 2 $ 4 $ — $ 3 (1) Included in Operation and maintenance expense in the Registrants’ Condensed Statements of Consolidated Income. (2) Included in Other, net in the Registrants’ Condensed Statements of Consolidated Income.
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	Changes in accumulated other comprehensive loss related to defined benefit and postretirement plans are as follows: CenterPoint Energy Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Beginning Balance $ (65 ) $ (71 ) $ (66 ) $ (72 ) Amounts reclassified from accumulated other comprehensive loss: Prior service cost (1) 1 1 1 1 Actuarial losses (1) 1 1 3 3 Tax expense — (1 ) (1 ) (2 ) Net current period other comprehensive income 2 1 3 2 Ending Balance $ (63 ) $ (70 ) $ (63 ) $ (70 ) (1) These accumulated other comprehensive components are included in the computation of net periodic cost.

Regulatory Accounting (Tables)

Regulatory Accounting (Tables)	6 Months Ended
	Jun. 30, 2018
Regulatory Assets and Liabilities, Other Disclosures [Abstract]
Schedule of Regulatory Assets and Liabilities [Table Text Block]	The following is a list of regulatory assets and liabilities reflected on the Registrants’ Condensed Consolidated Balance Sheets: June 30, 2018 December 31, 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC Regulatory Assets: (in millions) Current regulatory assets (1) $ 55 $ — $ 55 $ 130 $ — $ 130 Non-current regulatory assets: Securitized regulatory assets 1,293 1,293 — 1,590 1,590 — Unrecognized equity return (2) (242 ) (242 ) — (287 ) (287 ) — Unamortized loss on reacquired debt 72 72 — 75 75 — Pension and postretirement-related regulatory asset (3) 623 32 18 646 31 20 Hurricane Harvey restoration costs (4) 63 56 7 64 58 6 Regulatory assets related to TCJA (5) 48 33 15 48 33 15 Other long-term regulatory assets (6) 210 77 133 211 70 140 Total non-current regulatory assets 2,067 1,321 173 2,347 1,570 181 Total regulatory assets 2,122 1,321 228 2,477 1,570 311 Regulatory Liabilities: Current regulatory liabilities (7) 43 6 37 24 22 2 Non-current regulatory liabilities: Regulatory liabilities related to TCJA (5) 1,389 885 504 1,354 862 492 Estimated removal costs 885 279 606 878 285 593 Other long-term regulatory liabilities 247 101 146 232 116 116 Total non-current regulatory liabilities 2,521 1,265 1,256 2,464 1,263 1,201 Total regulatory liabilities 2,564 1,271 1,293 2,488 1,285 1,203 Total regulatory assets and liabilities, net $ (442 ) $ 50 $ (1,065 ) $ (11 ) $ 285 $ (892 ) (1) Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ Condensed Consolidated Balance Sheets. (2) The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended June 30, 2018 and 2017 , CenterPoint Energy and Houston Electric recognized approximately $24 million and $10 million , respectively, of the allowed equity return. During the six months ended June 30, 2018 and 2017 , CenterPoint Energy and Houston Electric recognized approximately $45 million and $17 million , respectively, of the allowed equity return. The timing of CenterPoint Energy’s and Houston Electric’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months. (3) Includes a portion of NGD’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates that is being deferred for rate making purposes, of which $5 million and $7 million as of June 30, 2018 and December 31, 2017 , respectively, were not earning a return. (4) The Registrants are not earning a return on Hurricane Harvey restoration costs. (5) The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities. (6) Other long-term regulatory assets that are not earning a return were not material as of June 30, 2018 and December 31, 2017 . (7) Current regulatory liabilities are included in Other current liabilities in the Registrants’ Condensed Consolidated Balance Sheets.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	The table below summarizes CenterPoint Energy’s and CERC’s current weather hedge activity: Three Months Ended June 30, Six Months Ended June 30, Jurisdiction Winter Season Bilateral Cap 2018 2017 2018 2017 (in millions) Certain NGD jurisdictions 2018 – 2019 $ 9 $ — $ — $ — $ — Certain NGD jurisdictions 2017 – 2018 8 — — — — Total CERC (1) — — — — Electric operations’ service territory 2018 – 2019 8 — — — — Electric operations’ service territory 2017 – 2018 9 — — (4 ) — Electric operations’ service territory 2016 – 2017 9 — — — 1 Total CenterPoint Energy (1) $ — $ — $ (4 ) $ 1 (1) Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income.
Fair Value of Derivative Instruments [Table Text Block]	The following tables present information about derivative instruments and hedging activities. The first two tables provide a balance sheet overview of Derivative Assets and Liabilities, while the last table provides a breakdown of the related income statement impacts. Fair Value of Derivative Instruments (CenterPoint Energy and CERC) June 30, 2018 December 31, 2017 Balance Sheet Location Derivative Assets Fair Value Derivative Liabilities Fair Value Derivative Assets Fair Value Derivative Liabilities Fair Value Derivatives designated as fair value hedges: (in millions) Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities $ — $ 3 $ 13 $ 1 Derivatives not designated as hedging instruments: Natural gas derivatives (1) (2) (3) Current Assets: Non-trading derivative assets 76 2 114 4 Natural gas derivatives (1) (2) (3) Other Assets: Non-trading derivative assets 46 — 44 — Natural gas derivatives (1) (2) (3) Current Liabilities: Non-trading derivative liabilities 23 64 38 78 Natural gas derivatives (1) (2) (3) Other Liabilities: Non-trading derivative liabilities 15 41 9 24 Total CERC 160 110 218 107 Indexed debt securities derivative Current Liabilities — 641 — 668 Total CenterPoint Energy $ 160 $ 751 $ 218 $ 775 (1) The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,862 Bcf or a net 268 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of June 30, 2018 and December 31, 2017 , respectively. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure. (2) Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $82 million asset and a $130 million asset as of June 30, 2018 and December 31, 2017 , respectively, as shown on CenterPoint Energy’s and CERC’s Condensed Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, impacted by collateral netting of $32 million and $19 million , respectively. (3) Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
Offsetting of Natural Gas Derivative Assets and Liabilities [Table Text Block]	Offsetting of Natural Gas Derivative Assets and Liabilities (CenterPoint Energy and CERC) June 30, 2018 December 31, 2017 Gross Amounts Recognized (1) Gross Amounts Offset in the Consolidated Balance Sheets Net Amount Presented in the Consolidated Balance Sheets (2) Gross Amounts Recognized (1) Gross Amounts Offset in the Consolidated Balance Sheets Net Amount Presented in the Consolidated Balance Sheets (2) (in millions) Current Assets: Non-trading derivative assets $ 99 $ (25 ) $ 74 $ 165 $ (55 ) $ 110 Other Assets: Non-trading derivative assets 61 (15 ) 46 53 (9 ) 44 Current Liabilities: Non-trading derivative liabilities (69 ) 43 (26 ) (83 ) 63 (20 ) Other Liabilities: Non-trading derivative liabilities (41 ) 29 (12 ) (24 ) 20 (4 ) Total $ 50 $ 32 $ 82 $ 111 $ 19 $ 130 (1) Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements. (2) The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
Income Statement Impact of Derivative Activity [Table Text Block]	Hedge ineffectiveness is recorded as a component of natural gas expense and primarily results from differences in the location of the derivative instrument and the hedged item. Basis ineffectiveness arises from natural gas market price differences between the locations of the hedged inventory and the delivery location specified in the hedge instruments. The impact of natural gas derivatives designated as fair value hedges, the related hedged item, and natural gas derivatives not designated as hedging instruments are presented in the table below. Income Statement Impact of Derivative Activity (CenterPoint Energy and CERC) Three Months Ended June 30, Six Months Ended June 30, Income Statement Location 2018 2017 2018 2017 Derivatives designated as fair value hedges: (in millions) Natural gas derivatives Gains (Losses) in Non-utility natural gas expense $ 13 $ 3 $ 13 $ 12 Natural gas inventory Gains (Losses) in Non-utility natural gas expense (12 ) (4 ) (14 ) (14 ) Total CenterPoint Energy and CERC (1) $ 1 $ (1 ) $ (1 ) $ (2 ) Derivatives not designated as hedging instruments: Natural gas derivatives Gains (Losses) in Non-utility revenues $ 11 $ 36 $ 68 $ 132 Natural gas derivatives Gains (Losses) in Non-utility natural gas expense (9 ) (9 ) (78 ) (82 ) Total CERC 2 27 (10 ) 50 Indexed debt securities derivative Gains (Losses) in Other Income (Expense) (254 ) (13 ) (272 ) (23 ) Total CenterPoint Energy $ (252 ) $ 14 $ (282 ) $ 27 (1) Hedge ineffectiveness results from the basis ineffectiveness discussed above, and excludes the impact to natural gas expense from timing ineffectiveness. Timing ineffectiveness arises due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity. As the commodity contract nears the settlement date, spot-to-forward price differences should converge, which should reduce or eliminate the impact of this ineffectiveness on natural gas expense.
Disclosure of Credit Derivatives [Table Text Block]	CenterPoint Energy and CERC enter into financial derivative contracts containing material adverse change provisions. These provisions could require CenterPoint Energy or CERC to post additional collateral if the S&P or Moody’s credit ratings of CenterPoint Energy, Inc. or its subsidiaries, including CERC Corp., are downgraded. CenterPoint Energy and CERC June 30, December 31, 2017 (in millions) Aggregate fair value of derivatives containing material adverse change provisions in a net liability position $ 2 $ 2 Fair value of collateral already posted — — Additional collateral required to be posted if credit risk contingent features triggered 1 2

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair value, assets and liabilities measured on a recurring basis [Table Text Block]	The following tables present information about the Registrants’ assets and liabilities (including derivatives that are presented net) measured at fair value on a recurring basis and indicate the fair value hierarchy of the valuation techniques utilized by the Registrants to determine such fair value. CenterPoint Energy June 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting (1) Total Level 1 Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 586 $ — $ — $ — $ 586 $ 963 $ — $ — $ — $ 963 Investments, including money market funds (2) 70 — — — 70 68 — — — 68 Natural gas derivatives (3) — 142 18 (40 ) 120 — 161 57 (64 ) 154 Hedged portion of natural gas inventory — — — — — 14 — — — 14 Total assets $ 656 $ 142 $ 18 $ (40 ) $ 776 $ 1,045 $ 161 $ 57 $ (64 ) $ 1,199 Liabilities Indexed debt securities derivative $ — $ — $ 641 $ — $ 641 $ — $ — $ 668 $ — $ 668 Natural gas derivatives (3) — 105 5 (72 ) 38 — 96 11 (83 ) 24 Hedged portion of natural gas inventory 1 — — — 1 — — — — — Total liabilities $ 1 $ 105 $ 646 $ (72 ) $ 680 $ — $ 96 $ 679 $ (83 ) $ 692 Houston Electric June 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting Total Level 1 Level 2 Level 3 Netting Total Assets (in millions) Investments, including money market funds (2) $ 52 $ — $ — $ — $ 52 $ 51 $ — $ — $ — $ 51 Total assets $ 52 $ — $ — $ — $ 52 $ 51 $ — $ — $ — $ 51 CERC June 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Netting (1) Total Level 1 Level 2 Level 3 Netting (1) Total Assets (in millions) Corporate equities $ 2 $ — $ — $ — $ 2 $ 3 $ — $ — $ — $ 3 Investments, including money market funds (2) 11 — — — 11 11 — — — 11 Natural gas derivatives (3) — 142 18 (40 ) 120 — 161 57 (64 ) 154 Hedged portion of natural gas inventory — — — — — 14 — — — 14 Total assets $ 13 $ 142 $ 18 $ (40 ) $ 133 $ 28 $ 161 $ 57 $ (64 ) $ 182 Liabilities Natural gas derivatives (3) $ — $ 105 $ 5 $ (72 ) $ 38 $ — $ 96 $ 11 $ (83 ) $ 24 Hedged portion of natural gas inventory 1 — — — 1 — — — — — Total liabilities $ 1 $ 105 $ 5 $ (72 ) $ 39 $ — $ 96 $ 11 $ (83 ) $ 24 (1) Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy and CERC to settle positive and negative positions and also include cash collateral of $32 million and $19 million as of June 30, 2018 and December 31, 2017 , respectively, posted with the same counterparties. (2) Amounts are included in Prepaid expenses and other current assets in the Condensed Consolidated Balance Sheets. (3) Natural gas derivatives include no material amounts related to physical forward transactions with Enable.
Assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs [Table Text Block]	The following table presents additional information about assets or liabilities, including derivatives that are measured at fair value on a recurring basis for which CenterPoint Energy and CERC have utilized Level 3 inputs to determine fair value: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC CenterPoint Energy CERC (in millions) Beginning balance $ (662 ) $ 12 $ (700 ) $ 27 $ (622 ) $ 46 $ (704 ) $ 13 Total gains (losses) (11 ) 1 (6 ) 7 (16 ) 3 — 23 Total settlements 44 (1 ) — — 11 (35 ) (4 ) (4 ) Transfers into Level 3 1 1 1 1 1 1 2 2 Transfers out of Level 3 — — (7 ) (7 ) (2 ) (2 ) (6 ) (6 ) Ending balance (1) $ (628 ) $ 13 $ (712 ) $ 28 $ (628 ) $ 13 $ (712 ) $ 28 The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date: $ (9 ) $ 3 $ (9 ) $ 4 $ (23 ) $ (4 ) $ (2 ) $ 21 (1) CenterPoint Energy and CERC did not have significant Level 3 sales or purchases during either of the three or six months ended June 30, 2018 or 2017 .
Estimated fair value of financial instruments, debt instruments [Table Text Block]	The fair values of cash and cash equivalents, investments in debt and equity securities classified as “trading” and short-term borrowings are estimated to be approximately equivalent to carrying amounts and have been excluded from the table below. The carrying amounts of non-trading derivative assets and liabilities and CenterPoint Energy’s ZENS indexed debt securities derivative are stated at fair value and are excluded from the table below. The fair value of each debt instrument is determined by multiplying the principal amount of each debt instrument by a combination of historical trading prices and comparable issue data. These liabilities, which are not measured at fair value in the Registrants’ Condensed Consolidated Balance Sheets, but for which the fair value is disclosed, would be classified as Level 2 in the fair value hierarchy. June 30, 2018 December 31, 2017 CenterPoint Energy (1) Houston Electric (1) CERC CenterPoint Energy (1) Houston Electric (1) CERC Long-term debt, including current maturities (in millions) Carrying amount $ 8,256 $ 4,919 $ 2,722 $ 8,679 $ 4,753 $ 2,457 Fair value 8,470 4,991 2,876 9,220 5,034 2,708 (1) Includes Securitization Bond debt.

Unconsolidated Affiliate (Cen33

Unconsolidated Affiliate (CenterPoint Energy and CERC) (Tables)	6 Months Ended
	Jun. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments [Table Text Block]	Limited Partner Interest and Units Held in Enable: June 30, 2018 Limited Partner Interest (1) Common Units Series A Preferred Units (2) CERC Corp. 54.0 % 233,856,623 — OGE 25.6 % 110,982,805 — Public unitholders 20.4 % 88,225,208 — CenterPoint Energy — — 14,520,000 Total units outstanding 100.0 % 433,064,636 14,520,000 (1) Excluding the Series A Preferred Units owned by CenterPoint Energy. (2) The carrying amount of the Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both June 30, 2018 and December 31, 2017 . No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion. Summarized unaudited consolidated income information for Enable is as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Operating revenues $ 805 $ 626 $ 1,553 $ 1,292 Cost of sales, excluding depreciation and amortization 444 279 819 587 Operating income 126 122 265 262 Net income attributable to Enable 86 86 191 197 Reconciliation of Equity in Earnings, net: CenterPoint Energy’s and CERC’s interest $ 46 $ 47 $ 103 $ 107 Basis difference amortization (1) 12 12 24 24 CenterPoint Energy’s and CERC’s equity in earnings, net $ 58 $ 59 $ 127 $ 131 (1) Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s and CERC’s share of Enable’s earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s and CERC’s original investment in Enable and their underlying equity in Enable’s net assets. The basis difference is amortized over approximately 31 years, the average life of the assets to which the basis difference is attributed. Summarized unaudited consolidated balance sheet information for Enable is as follows: June 30, December 31, 2017 (in millions) Current assets $ 432 $ 416 Non-current assets 11,360 11,177 Current liabilities 1,258 1,279 Non-current liabilities 2,963 2,660 Non-controlling interest 11 12 Preferred equity 362 362 Enable partners’ equity 7,198 7,280 Reconciliation of Investment in Enable: CenterPoint Energy’s and CERC’s ownership interest in Enable partners’ equity $ 3,887 $ 3,935 CenterPoint Energy’s and CERC’s basis difference (1,436 ) (1,463 ) CenterPoint Energy’s and CERC’s equity method investment in Enable $ 2,451 $ 2,472 Distributions Received from Enable: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Investment in Enable common units $ 75 $ 75 $ 149 $ 149 Total CERC 75 75 149 149 Investment in Enable Series A Preferred Units 9 9 18 18 Total CenterPoint Energy $ 84 $ 84 $ 167 $ 167 Transactions with Enable (CenterPoint Energy and CERC): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Reimbursement of transition services (1) $ 1 $ 1 $ 3 $ 3 Natural gas expenses, including transportation and storage costs 29 24 66 57 (1) Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement. June 30, 2018 December 31, 2017 (in millions) Accounts receivable for amounts billed for transition services $ 3 $ 1 Accounts payable for natural gas purchases from Enable 8 13

Goodwill and Other Intangible34

Goodwill and Other Intangibles (CenterPoint Energy and CERC) (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	CenterPoint Energy’s and CERC’s goodwill by reportable business segment as of both June 30, 2018 and December 31, 2017 is as follows: (in millions) Natural Gas Distribution $ 746 Energy Services (1) 110 Other Operations 11 Total $ 867 (1) Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012.
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The tables below present information on CenterPoint Energy’s and CERC’s other intangible assets recorded in Other non-current assets on the Condensed Consolidated Balance Sheets. June 30, 2018 December 31, 2017 Useful Lives Gross Carrying Amount Accumulated Amortization Net Balance Gross Carrying Amount Accumulated Amortization Net Balance (in years) (in millions) Customer relationships 15 $ 86 $ (25 ) $ 61 $ 86 $ (21 ) $ 65 Covenants not to compete 4 4 (2 ) 2 4 (2 ) 2 Other Various 15 (9 ) 6 15 (8 ) 7 Total $ 105 $ (36 ) $ 69 $ 105 $ (31 ) $ 74
Finite-lived Intangible Assets Amortization Expense [Table Text Block]	Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Amortization expense of intangible assets $ 2 $ 1 $ 5 $ 3

Indexed Debt Securities (ZENS35

Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) (Tables)	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Indexed Debt Securities and Marketable Securities [Table Text Block]	In 1995, CenterPoint Energy sold a cable television subsidiary to TW and received certain TW securities as partial consideration. A subsidiary of CenterPoint Energy holds shares of certain securities detailed in the table below, which are classified as trading securities and are expected to be held to facilitate CenterPoint Energy’s ability to meet its obligation under the ZENS. Unrealized gains and losses resulting from changes in the market value of the ZENS-Related Securities are recorded in CenterPoint Energy’s Condensed Statements of Consolidated Income. Shares Held June 30, 2018 December 31, 2017 AT&T Common 10,212,945 — Charter Common 872,503 872,503 Time Common — 888,392 TW Common — 7,107,130 As a result, CenterPoint Energy recorded the following during the six months ended June 30, 2018 : Meredith/Time AT&T/TW (in millions) (in millions) Cash payment to ZENS note holders $ 16 Due to ZENS note holders (1) $ 382 Indexed debt – reduction (4 ) Indexed debt – reduction (95 ) Indexed debt securities derivative – reduction (1 ) Indexed debt securities derivative – reduction (45 ) Loss on indexed debt securities $ 11 Loss on indexed debt securities $ 242 (1) Cash of approximately $382 million was paid to ZENS note holders in July 2018. CenterPoint Energy’s reference shares for each ZENS consisted of the following: June 30, 2018 December 31, 2017 (in shares) AT&T Common 0.7185 — Charter Common 0.061382 0.061382 Time Common — 0.0625 TW Common — 0.5

Short-Term Borrowings and Lon36

Short-Term Borrowings and Long-term Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Schedule of Debt [Table Text Block]	Debt Issuances. During the six months ended June 30, 2018 , the following debt instruments were issued: Issuance Date Debt Instrument Aggregate Principal Amount Interest Rate Maturity Date (in millions) Houston Electric February 2018 General mortgage bonds $ 400 3.95% 2048 CERC Corp. March 2018 Unsecured senior notes 300 3.55% 2023 CERC Corp. March 2018 Unsecured senior notes 300 4.00% 2028
Schedule of Line of Credit Facilities [Table Text Block]	The Registrants had the following revolving credit facilities and utilization of such facilities: June 30, 2018 December 31, 2017 Size of Loans Letters Commercial Weighted Average Interest Rate Loans Letters Commercial Weighted Average Interest Rate (in millions, except weighted average interest rate) CenterPoint Energy $ 1,700 (1) $ — $ 6 $ — — % $ — $ 6 $ 855 1.88 % Houston Electric 300 — 4 — — — 4 — — CERC Corp. 900 — 1 565 2.37 % — 1 898 1.72 % Total $ 2,900 $ — $ 11 $ 565 $ — $ 11 $ 1,753 (1) Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility will increase to $3.3 billion upon the satisfaction of certain conditions described above. Execution Date Company Size of Facility Draw Rate of LIBOR plus (1) Financial Covenant Limit on Debt for Borrowed Money to Capital Ratio Debt for Borrowed Money to Capital Ratio as of June 30, 2018 (2) Termination Date (in millions) March 3, 2016 CenterPoint Energy $ 1,700 (3) 1.250% 75% (4) (5) 52.1% March 3, 2022 March 3, 2016 Houston Electric 300 1.125% 65% (5) 50.7% March 3, 2022 March 3, 2016 CERC Corp. 900 1.250% 65% 37.8% March 3, 2022 (1) Based on current credit ratings. (2) As defined in the revolving credit facility agreement, excluding Securitization Bonds. (3) Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility will increase to $3.3 billion upon the satisfaction of certain conditions described above. (4) CenterPoint Energy’s financial covenant limit will return to 65% upon the earlier of (i) June 30, 2019 or (ii) the termination of all commitments in respect of the Bridge Facility without any borrowing thereunder. (5) For CenterPoint Energy (whenever its financial covenant limit is 65% ) and Houston Electric, the financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive 12 -month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date CenterPoint Energy delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of CenterPoint Energy’s certification or (iii) the revocation of such certification.

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The Registrants reported the following effective tax rates: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 CenterPoint Energy 15 % 36 % 27 % 36 % Houston Electric 21 % 36 % 22 % 36 % CERC 22 % 35 % 22 % 37 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Long-term Purchase Commitment [Table Text Block]	As of June 30, 2018 , minimum payment obligations for natural gas supply commitments are approximately: (in millions) Remaining six months of 2018 $ 185 2019 264 2020 168 2021 82 2022 51 2023 and beyond 123

Earnings Per Share (CenterPoi39

Earnings Per Share (CenterPoint Energy) (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table reconciles numerators and denominators of CenterPoint Energy’s basic and diluted earnings (loss) per share calculations: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions, except share and per share amounts) Net income (loss) $ (75 ) $ 135 $ 90 $ 327 Basic weighted average shares outstanding 431,523,000 430,996,000 431,378,000 430,896,000 Plus: Incremental shares from assumed conversions: Restricted stock (1) — 2,801,000 3,029,000 2,801,000 Diluted weighted average shares 431,523,000 433,797,000 434,407,000 433,697,000 Basic earnings (loss) per share Net income (loss) $ (0.17 ) $ 0.31 $ 0.21 $ 0.76 Diluted earnings (loss) per share Net income (loss) $ (0.17 ) $ 0.31 $ 0.21 $ 0.75 (1) 3,029,000 incremental shares from assumed conversions of restricted stock have not been included in the computation of diluted earnings (loss) per share for the three months ended June 30, 2018 as their inclusion would be anti-dilutive.

Reportable Business Segments (T

Reportable Business Segments (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Reportable business segments by Registrant are as follows: Electric Transmission & Distribution Natural Gas Distribution Energy Services Midstream Investments Other Operations CenterPoint Energy X X X X X Houston Electric X CERC X X X X Financial data for business segments is as follows: CenterPoint Energy Three Months Ended June 30, 2018 2017 Revenues from Net Operating (Loss) Revenues from Net Operating (in millions) Electric Transmission & Distribution $ 854 (1) $ — $ 181 $ 752 (1) $ — $ 171 Natural Gas Distribution 487 8 7 470 7 42 Energy Services 841 19 15 918 13 16 Midstream Investments (2) — — — — — — Other Operations 4 — (16 ) 3 — 11 Eliminations — (27 ) — — (20 ) — Consolidated $ 2,186 $ — $ 187 $ 2,143 $ — $ 240 Six Months Ended June 30, 2018 2017 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Revenues from External Customers Net Intersegment Revenues Operating (in millions) Electric Transmission & Distribution $ 1,605 (1) $ — $ 296 $ 1,391 (1) $ — $ 257 Natural Gas Distribution 1,630 18 163 1,377 16 210 Energy Services 2,098 47 (11 ) 2,103 24 51 Midstream Investments (2) — — — — — — Other Operations 8 — (10 ) 7 — 13 Eliminations — (65 ) — — (40 ) — Consolidated $ 5,341 $ — $ 438 $ 4,878 $ — $ 531 (1) CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Affiliates of NRG $ 169 $ 167 $ 330 $ 319 Affiliates of Vistra Energy Corp. 59 53 113 100 CERC Three Months Ended June 30, 2018 2017 Revenues from Net Operating Revenues from Net Operating (in millions) Natural Gas Distribution $ 487 $ 8 $ 7 $ 470 $ 7 $ 42 Energy Services 841 19 15 918 13 16 Midstream Investments (2) — — — — — — Other Operations — — — (1 ) — 1 Eliminations — (27 ) — — (20 ) — Consolidated $ 1,328 $ — $ 22 $ 1,387 $ — $ 59 Six Months Ended June 30, 2018 2017 Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) Revenues from External Customers Net Intersegment Revenues Operating Income (Loss) (in millions) Natural Gas Distribution $ 1,630 $ 18 $ 163 $ 1,377 $ 16 $ 210 Energy Services 2,098 47 (11 ) 2,103 24 51 Midstream Investments (2) — — — — — — Other Operations — — 1 — — (3 ) Eliminations — (65 ) — — (40 ) — Consolidated $ 3,728 $ — $ 153 $ 3,480 $ — $ 258 (2) CenterPoint Energy’s and CERC’s Midstream Investments’ equity earnings, net are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Enable $ 58 $ 59 $ 127 $ 131 CenterPoint Energy and CERC Total Assets June 30, 2018 December 31, 2017 CenterPoint Energy CERC CenterPoint CERC (in millions) Electric Transmission & Distribution $ 10,430 $ — $ 10,292 $ — Natural Gas Distribution 6,501 6,501 6,608 6,608 Energy Services 1,256 1,256 1,521 1,521 Midstream Investments 2,451 2,451 2,472 2,472 Other Operations 2,311 (3) 89 2,497 (3) 70 Eliminations (841 ) (655 ) (654 ) (559 ) Consolidated $ 22,108 $ 9,642 $ 22,736 $ 10,112 (3) Includes pension and other postemployment-related regulatory assets of $577 million and $600 million , respectively, as of June 30, 2018 and December 31, 2017 .
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Affiliates of NRG $ 169 $ 167 $ 330 $ 319 Affiliates of Vistra Energy Corp. 59 53 113 100
Midstream Investments [Table Text Block]	CenterPoint Energy’s and CERC’s Midstream Investments’ equity earnings, net are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Enable $ 58 $ 59 $ 127 $ 131

Supplemental Disclosure of Ca41

Supplemental Disclosure of Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]	The table below provides supplemental disclosure of cash flow information: Six Months Ended June 30, 2018 2017 CenterPoint Energy Houston Electric CERC CenterPoint Energy Houston Electric CERC (in millions) Cash Payments/Receipts: Interest, net of capitalized interest $ 167 $ 90 $ 50 $ 182 $ 94 $ 56 Income taxes, net 88 120 3 11 76 3 Non-cash transactions: Accounts payable related to capital expenditures 133 75 69 106 75 44 The table below provides a reconciliation of cash, cash equivalents and restricted cash reported in the Condensed Consolidated Balance Sheets to the amount reported in the Condensed Statements of Consolidated Cash Flows: June 30, 2018 December 31, 2017 CenterPoint Energy Houston Electric CenterPoint Energy Houston Electric (in millions) Cash and cash equivalents $ 328 $ 253 $ 260 $ 238 Restricted cash included in Prepaid expenses and other current assets 37 37 35 35 Restricted cash included in Other 1 1 1 1 Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows $ 366 $ 291 $ 296 $ 274 CERC does not have restricted cash and therefore was not included in the table above.

Related Party Transactions (H42

Related Party Transactions (Houston Electric and CERC) (Tables)	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Schedule of Money Pool Investment and Borrowing [Table Text Block]	The table below summarizes money pool activity: June 30, 2018 December 31, 2017 Houston Electric CERC Houston Electric CERC (in millions) Money pool investments (borrowings) (1) $ 26 $ — $ (60 ) $ (570 ) Weighted average interest rate 2.00 % — % 1.90 % 1.90 % (1) Included in Accounts and notes receivable (payable)–affiliated companies in the Condensed Consolidated Balance Sheets.
Schedule of Related Party Transactions [Table Text Block]	Amounts charged for these services were as follows and are included primarily in operation and maintenance expenses: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Corporate service charges $ 47 $ 35 $ 44 $ 32 $ 91 $ 69 $ 86 $ 63 Net affiliate service charges (billings) (3 ) 3 (4 ) 4 (5 ) 5 (5 ) 5 Houston Electric and CERC paid dividends on their common shares and stock, respectively, to Utility Holding, LLC as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Houston Electric CERC Houston Electric CERC Houston Electric CERC Houston Electric CERC (in millions) Dividends paid $ 31 $ 125 $ 10 $ 140 $ 63 $ 211 $ 42 $ 248
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions) Affiliates of NRG $ 169 $ 167 $ 330 $ 319 Affiliates of Vistra Energy Corp. 59 53 113 100

Background and Basis of Prese43

Background and Basis of Presentation (Details)	Jun. 30, 2018stateshares
Enable Midstream Partners [Member]
Ownership percentage of equity method investment	54.00%
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Preferred units held | shares	14,520,000	[1]
Natural Gas Distribution [Member]
Number of states in which entity operates	6
Energy Services [Member]
Number of states in which entity operates	33
[1]	The carrying amount of the Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both June 30, 2018 and December 31, 2017. No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion.

New Accounting Pronouncements44

New Accounting Pronouncements (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accounting Standards Update 2016-15 [Member]
Effect of change on cash flow activities due to adoption of new ASU			$ 1	$ 3
Accounting Standards Update 2016-18 [Member]
Effect of change on cash flow activities due to adoption of new ASU			(2)	8
Accounting Standards Update 2017-07 [Member] | Operating Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	$ 15	$ 17	29	34
Accounting Standards Update 2017-07 [Member] | Other Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	(15)	(17)	(29)	(34)
Accounting Standards Update 2017-07 [Member] | Houston Electric [Member] | Operating Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	8	7	15	15
Accounting Standards Update 2017-07 [Member] | Houston Electric [Member] | Other Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	(8)	(7)	(15)	(15)
Accounting Standards Update 2017-07 [Member] | CERC Corp [Member] | Operating Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	4	6	8	11
Accounting Standards Update 2017-07 [Member] | CERC Corp [Member] | Other Income [Member]
Increase to operating income and corresponding (decrease) to other income from the adoption of ASU 2017-07	$ (4)	$ (6)	$ (8)	$ (11)

Proposed Merger with Vectren 45

Proposed Merger with Vectren (CenterPoint Energy) (Details) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Amount of cash to be paid to acquire Vectren	$ 6,000
Cash to be paid per share of Vectren common stock prior to closing of the Merger	$ 72
Short-term debt	$ 0	$ 39
Anticipated amount of short and long-term debt at the closing of the Merger	2,500
Vectren [Member]
Short-term debt	248
Long-term debt, including current maturities	2,000
Termination fee	150
CenterPoint Energy [Member]
Termination fee	$ 210

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue from contracts		$ 1,449	$ 1,338	$ 3,575	$ 3,050
Derivatives income		782	815	1,885	1,870
Other (3)	[1]	(18)	10	(54)	(2)
Total revenues		2,186	2,143	5,341	4,878
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(27)	(20)	(65)	(40)
Electric Transmission and Distribution [Member]
Disaggregation of Revenue [Line Items]
Total revenues	[2]	854	752	1,605	1,391
Electric Transmission and Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		0	0	0	0
Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Total revenues		487	470	1,630	1,377
Natural Gas Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(8)	(7)	(18)	(16)
Energy Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues		841	918	2,098	2,103
Energy Services [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(19)	(13)	(47)	(24)
Other Operations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		4	3	8	7
Other Operations [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		0	0	0	0
Reportable Subsegments [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	(8)	(7)	(18)	(16)
Derivatives income	[4]	(19)	(13)	(47)	(24)
Total revenues		(27)	(20)	(65)	(40)
Reportable Subsegments [Member] | Electric Transmission and Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	860	758	1,621	1,402
Derivatives income	[3]	0	0	(4)	1
Other (3)	[1],[3]	(6)	(6)	(12)	(12)
Total revenues	[3]	854	752	1,605	1,391
Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	509	463	1,695	1,388
Derivatives income	[3]	0	0	0	0
Other (3)	[1],[3]	(14)	14	(47)	5
Total revenues	[3]	487	470	1,630	1,377
Reportable Subsegments [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]	78	116	256	258
Derivatives income	[4]	782	815	1,889	1,869
Other (3)	[1],[4]	0	0	0	0
Total revenues	[4]	841	918	2,098	2,103
Reportable Subsegments [Member] | Other Operations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]	2	1	3	2
Derivatives income	[4]	0	0	0	0
Other (3)	[1],[4]	2	2	5	5
Total revenues	[4]	4	3	8	7
Houston Electric [Member]
Disaggregation of Revenue [Line Items]
Total revenues		854	752	1,609	1,390
Houston Electric [Member] | Reportable Subsegments [Member] | Electric Transmission and Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		860	758	1,621	1,402
Other (3)	[1]	(6)	(6)	(12)	(12)
Total revenues		854	752	1,609	1,390
CERC Corp [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts		587	579	1,951	1,646
Derivatives income		782	815	1,889	1,869
Other (3)	[1]	(14)	13	(47)	5
Total revenues		1,328	1,387	3,728	3,480
CERC Corp [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(27)	(20)	(65)	(40)
CERC Corp [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Total revenues		487	470	1,630	1,377
CERC Corp [Member] | Natural Gas Distribution [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(8)	(7)	(18)	(16)
CERC Corp [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Total revenues		841	918	2,098	2,103
CERC Corp [Member] | Energy Services [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		(19)	(13)	(47)	(24)
CERC Corp [Member] | Other Operations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		0	(1)	0	0
CERC Corp [Member] | Other Operations [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Total revenues		0	0	0	0
CERC Corp [Member] | Reportable Subsegments [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	(8)	(7)	(18)	(16)
Derivatives income	[4]	(19)	(13)	(47)	(24)
Total revenues		(27)	(20)	(65)	(40)
CERC Corp [Member] | Reportable Subsegments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[3]	509	463	1,695	1,388
Derivatives income	[3]	0	0	0	0
Other (3)	[1],[3]	(14)	14	(47)	5
Total revenues	[3]	487	470	1,630	1,377
CERC Corp [Member] | Reportable Subsegments [Member] | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]	78	116	256	258
Derivatives income	[4]	782	815	1,889	1,869
Other (3)	[1],[4]	0	0	0	0
Total revenues	[4]	841	918	2,098	2,103
CERC Corp [Member] | Reportable Subsegments [Member] | Other Operations [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts	[4]	0	0	0	0
Derivatives income	[4]	0	0	0	0
Other (3)	[1],[4]	0	(1)	0	0
Total revenues	[4]	$ 0	$ (1)	$ 0	$ 0
[1]	Primarily consists of income from ARPs and leases. ARPs are contracts between the utility and its regulators, not between the utility and a customer. The Registrants recognize ARP revenue as other revenues when the regulator-specified conditions for recognition have been met. Upon recovery of ARP revenue through incorporation in rates charged for utility service to customers, ARP revenue is reversed and recorded as revenue from contracts with customers. The recognition of ARP revenues and the reversal of ARP revenues upon recovery through rates charged for utility service may not occur in the same period.
[2]	CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows:
[3]	Reflected in Utility revenues in the Condensed Statements of Consolidated Income.
[4]	Reflected in Non-utility revenues in the Condensed Statements of Consolidated Income.

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan, Change in Accumulated Comprehensive Loss [Roll Forward]
Beginning Balance		$ (65)	$ (71)	$ (66)	$ (72)
Amounts reclassified from accumulated other comprehensive loss:
Prior service cost (1)	[1]	1	1	1	1
Actuarial losses (1)	[1]	1	1	3	3
Tax expense		0	(1)	(1)	(2)
Net current period other comprehensive income		2	1	3	2
Ending Balance		(63)	(70)	(63)	(70)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost		15	25	30	48
Total contributions expected in current year		67		67
Total contributions to the plans during the period		2		64
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost		2	2	3	4
Total contributions expected in current year		16		16
Total contributions to the plans during the period		3		7
Operation and maintenance expense [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	9	9	18	18
Operation and maintenance expense [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	1	1	1	1
Other, net [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	19	22	39	44
Expected return on plan assets (2)	[3]	(26)	(24)	(53)	(48)
Amortization of prior service cost (credit) (2)	[3]	2	3	4	5
Amortization of net loss (2)	[3]	11	15	22	29
Other, net [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	4	4	7	8
Expected return on plan assets (2)	[3]	(2)	(2)	(3)	(3)
Amortization of prior service cost (credit) (2)	[3]	(1)	(1)	(2)	(2)
Houston Electric [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost		(1)	0	(1)	0
Total contributions expected in current year		10		10
Total contributions to the plans during the period		2		4
Houston Electric [Member] | Operation and maintenance expense [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	0	0	0	0
Houston Electric [Member] | Other, net [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	2	2	4	4
Expected return on plan assets (2)	[3]	(1)	(1)	(2)	(2)
Amortization of prior service cost (credit) (2)	[3]	(2)	(1)	(3)	(2)
CERC Corp [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic cost		1	2	2	3
Total contributions expected in current year		5		5
Total contributions to the plans during the period		1		2
CERC Corp [Member] | Operation and maintenance expense [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost (1)	[2]	0	0	0	0
CERC Corp [Member] | Other, net [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost (2)	[3]	1	1	2	2
Expected return on plan assets (2)	[3]	(1)	0	(1)	0
Amortization of prior service cost (credit) (2)	[3]	$ 1	$ 1	$ 1	$ 1
[1]	These accumulated other comprehensive components are included in the computation of net periodic cost.
[2]	Included in Operation and maintenance expense in the Registrants’ Condensed Statements of Consolidated Income.
[3]	Included in Other, net in the Registrants’ Condensed Statements of Consolidated Income.

Regulatory Accounting (Details)

Regulatory Accounting (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Securitized regulatory assets		$ 1,293		$ 1,293		$ 1,590
Unrecognized equity return (2)	[1]	(242)		(242)		(287)
Unamortized loss on reacquired debt		72		72		75
Regulatory assets		2,067		2,067		2,347
Total regulatory assets		2,122		2,122		2,477
Regulatory liabilities		2,521		2,521		2,464
Total regulatory liabilities		2,564		2,564		2,488
Total regulatory assets and liabilities, net		(442)		(442)		(11)
Houston Electric [Member]
Securitized regulatory assets		1,293		1,293		1,590
Unrecognized equity return (2)	[1]	(242)		(242)		(287)
Unamortized loss on reacquired debt		72		72		75
Regulatory assets		1,321		1,321		1,570
Total regulatory assets		1,321		1,321		1,570
Regulatory liabilities		1,265		1,265		1,263
Total regulatory liabilities		1,271		1,271		1,285
Total regulatory assets and liabilities, net		50		50		285
Amount of allowed equity return on the true-up balance that was recognized in the period		24	$ 10	45	$ 17
CERC Corp [Member]
Securitized regulatory assets		0		0		0
Unrecognized equity return (2)	[1]	0		0		0
Unamortized loss on reacquired debt		0		0		0
Regulatory assets		173		173		181
Total regulatory assets		228		228		311
Regulatory liabilities		1,256		1,256		1,201
Total regulatory liabilities		1,293		1,293		1,203
Total regulatory assets and liabilities, net		(1,065)		(1,065)		(892)
Hurricane Harvey [Member]
Regulatory assets	[2]	63		63		64
Hurricane Harvey [Member] | Houston Electric [Member]
Regulatory assets	[2]	56		56		58
Hurricane Harvey [Member] | CERC Corp [Member]
Regulatory assets	[2]	7		7		6
Prepaid expenses and other current assets [Member]
Current regulatory assets (1)	[3]	55		55		130
Prepaid expenses and other current assets [Member] | Houston Electric [Member]
Current regulatory assets (1)	[3]	0		0		0
Prepaid expenses and other current assets [Member] | CERC Corp [Member]
Current regulatory assets (1)	[3]	55		55		130
Other current liabilities [Member]
Current regulatory liabilities (7)	[4]	43		43		24
Other current liabilities [Member] | Houston Electric [Member]
Current regulatory liabilities (7)	[4]	6		6		22
Other current liabilities [Member] | CERC Corp [Member]
Current regulatory liabilities (7)	[4]	37		37		2
Pension and Other Postretirement Plans Costs [Member]
Regulatory assets	[5]	623		623		646
Pension and Other Postretirement Plans Costs [Member] | Houston Electric [Member]
Regulatory assets	[5]	32		32		31
Pension and Other Postretirement Plans Costs [Member] | CERC Corp [Member]
Regulatory assets	[5]	18		18		20
Amounts related to TCJA [Member]
Regulatory assets	[6]	48		48		48
Amounts related to TCJA [Member] | Houston Electric [Member]
Regulatory assets	[6]	33		33		33
Amounts related to TCJA [Member] | CERC Corp [Member]
Regulatory assets	[6]	15		15		15
Other Regulatory Assets (Liabilities) [Member]
Regulatory assets	[7]	210		210		211
Other Regulatory Assets (Liabilities) [Member] | Houston Electric [Member]
Regulatory assets	[7]	77		77		70
Other Regulatory Assets (Liabilities) [Member] | CERC Corp [Member]
Regulatory assets	[7]	133		133		140
Amounts related to TCJA [Member]
Regulatory liabilities	[6]	1,389		1,389		1,354
Amounts related to TCJA [Member] | Houston Electric [Member]
Regulatory liabilities	[6]	885		885		862
Amounts related to TCJA [Member] | CERC Corp [Member]
Regulatory liabilities	[6]	504		504		492
Removal Costs [Member]
Regulatory liabilities		885		885		878
Removal Costs [Member] | Houston Electric [Member]
Regulatory liabilities		279		279		285
Removal Costs [Member] | CERC Corp [Member]
Regulatory liabilities		606		606		593
Other Regulatory Assets (Liabilities) [Member]
Regulatory liabilities		247		247		232
Other Regulatory Assets (Liabilities) [Member] | Houston Electric [Member]
Regulatory liabilities		101		101		116
Other Regulatory Assets (Liabilities) [Member] | CERC Corp [Member]
Regulatory liabilities		146		146		116
Natural Gas Distribution [Member] | Pension and Other Postretirement Plans Costs [Member]
Remaining amounts of regulatory assets for which no return on investment during recovery period is provided		$ 5		$ 5		$ 7
[1]	The unrecognized equity return will be recognized as it is recovered in rates through 2024. During the three months ended June 30, 2018 and 2017, CenterPoint Energy and Houston Electric recognized approximately $24 million and $10 million, respectively, of the allowed equity return. During the six months ended June 30, 2018 and 2017, CenterPoint Energy and Houston Electric recognized approximately $45 million and $17 million, respectively, of the allowed equity return. The timing of CenterPoint Energy’s and Houston Electric’s recognition of the equity return will vary each period based on amounts actually collected during the period. The actual amounts recognized are adjusted at least annually to correct any over-collections or under-collections during the preceding 12 months.
[2]	The Registrants are not earning a return on Hurricane Harvey restoration costs.
[3]	Current regulatory assets are included in Prepaid expenses and other current assets in the Registrants’ Condensed Consolidated Balance Sheets.
[4]	Current regulatory liabilities are included in Other current liabilities in the Registrants’ Condensed Consolidated Balance Sheets.
[5]	Includes a portion of NGD’s actuarially determined pension and other postemployment expense in excess of the amount being recovered through rates that is being deferred for rate making purposes, of which $5 million and $7 million as of June 30, 2018 and December 31, 2017, respectively, were not earning a return.
[6]	The EDIT and deferred revenues will be recovered or refunded to customers as required by tax and regulatory authorities.
[7]	Other long-term regulatory assets that are not earning a return were not material as of June 30, 2018 and December 31, 2017.

Derivative Instruments Derivati

Derivative Instruments Derivatives and hedging (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 26, 2018	Feb. 28, 2018
Derivatives, Fair Value [Line Items]
Weather hedges term				10 years
Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges	[1]	$ 0	$ 0	$ (4)	$ 1
2018 to 2019 [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				9
2018 to 2019 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				8
2018 to 2019 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	0	0	0
2017 to 2018 [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				8
2017 to 2018 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				9
2017 to 2018 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	0	(4)	0
2016 to 2017 [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Weather hedge bilateral cap amount				9
2016 to 2017 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Electric Transmission and Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	0	0	1
Houston Electric [Member] | January thru February [Member] | Treasury Lock [Member]
Derivatives, Fair Value [Line Items]
Aggregate notional amount		200		200
Effective portion of realized gains (losses)				5
CERC Corp [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges	[1]	0	0	0	0
CERC Corp [Member] | 2018 to 2019 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	0	0	0
CERC Corp [Member] | 2017 to 2018 [Member] | Gains (Losses) in Revenue [Member] | Weather Hedge Swaps [Member] | Natural Gas Distribution [Member]
Derivatives, Fair Value [Line Items]
Recognized gain (loss) on weather hedges		0	$ 0	0	$ 0
CERC Corp [Member] | March [Member] | Treasury Lock [Member]
Derivatives, Fair Value [Line Items]
Aggregate notional amount		$ 450		450
Effective portion of realized gains (losses)				$ (1)
General Mortgage Bonds Due 2048 [Member] | Houston Electric [Member]
Derivatives, Fair Value [Line Items]
Principal amount of debt issued							$ 400
Senior Notes [Member] | CERC Corp [Member]
Derivatives, Fair Value [Line Items]
Principal amount of debt issued						$ 600
[1]	Weather hedge gains (losses) are recorded in Revenues in the Condensed Statements of Consolidated Income.

Derivative Instruments Deriva50

Derivative Instruments Derivative Fair Values (Details) $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)Bcf	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)Bcf
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		$ 160		$ 160		$ 218
Derivative Liabilities Fair Value		751		751		775
Gain (loss) on derivative instruments not designated as hedging instruments		(252)	$ 14	(282)	$ 27
Aggregate fair value of derivatives containing material adverse change provisions in a net liability position		2		2		2
Fair value of collateral already posted		0		0		0
Additional collateral required to be posted if credit risk contingent features triggered		1		1		$ 2
Gains (Losses) in Non-utility natural gas expense [Member]
Derivatives, Fair Value [Line Items]
Change in unrealized gain (loss) on hedged item in fair value hedge		(12)	(4)	(14)	(14)
Gain (loss) on fair value hedges recognized in earnings	[1]	1	(1)	$ (1)	(2)
Energy Related Derivative [Member]
Derivatives, Fair Value [Line Items]
Derivative gross volume notional amount (in Bcf) | Bcf				1,862		1,795
Net amount presented in the consolidated balance sheets	[2]	82		$ 82		$ 130
Gross Amounts Recognized	[3]	50		50		111
Gross Amounts Offset in the Consolidated Balance Sheets		32		32		19
Energy Related Derivative [Member] | Gains (Losses) in Non-utility natural gas expense [Member]
Derivatives, Fair Value [Line Items]
Change in unrealized gain (loss) on fair value hedging instruments		13	3	13	12
Energy Related Derivative [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[3]	99		99		165
Gross Amounts Offset		(25)		(25)		(55)
Derivative Asset	[2]	74		74		110
Energy Related Derivative [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[3]	61		61		53
Gross Amounts Offset		(15)		(15)		(9)
Derivative Asset	[2]	46		46		44
Energy Related Derivative [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[3]	(69)		(69)		(83)
Gross Amounts Offset		43		43		63
Derivative Liability	[2]	(26)		(26)		(20)
Energy Related Derivative [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts Recognized	[3]	(41)		(41)		(24)
Gross Amounts Offset		29		29		20
Derivative Liability	[2]	(12)		$ (12)		$ (4)
Energy Related Derivative [Member] | Long [Member]
Derivatives, Fair Value [Line Items]
Derivative gross volume notional amount (in Bcf) | Bcf				268		224
IDS Derivative [Member] | Gains (losses) in Other Income (Expense) [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments not designated as hedging instruments		(254)	(13)	$ (272)	(23)
IDS Derivative [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		0		0		$ 0
Derivative Liabilities Fair Value		641		641		668
CERC Corp [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value		160		160		218
Derivative Liabilities Fair Value		110		110		107
Gain (loss) on derivative instruments not designated as hedging instruments		2	27	(10)	50
CERC Corp [Member] | Energy Related Derivative [Member] | Gains (Losses) in Non-utility revenues [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments not designated as hedging instruments		11	36	68	132
CERC Corp [Member] | Energy Related Derivative [Member] | Gains (Losses) in Non-utility natural gas expense [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments not designated as hedging instruments		(9)	$ (9)	(78)	$ (82)
CERC Corp [Member] | Energy Related Derivative [Member] | Designated as Fair Value Hedge [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4],[5],[6]	0		0		13
Derivative Liabilities Fair Value	[4],[5],[6]	3		3		1
CERC Corp [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4],[5],[6]	76		76		114
Derivative Liabilities Fair Value	[4],[5],[6]	2		2		4
CERC Corp [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4],[5],[6]	46		46		44
Derivative Liabilities Fair Value	[4],[5],[6]	0		0		0
CERC Corp [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4],[5],[6]	23		23		38
Derivative Liabilities Fair Value	[4],[5],[6]	64		64		78
CERC Corp [Member] | Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets Fair Value	[4],[5],[6]	15		15		9
Derivative Liabilities Fair Value	[4],[5],[6]	$ 41		$ 41		$ 24
[1]	Hedge ineffectiveness results from the basis ineffectiveness discussed above, and excludes the impact to natural gas expense from timing ineffectiveness. Timing ineffectiveness arises due to changes in the difference between the spot price and the futures price, as well as the difference between the timing of the settlement of the futures and the valuation of the underlying physical commodity. As the commodity contract nears the settlement date, spot-to-forward price differences should converge, which should reduce or eliminate the impact of this ineffectiveness on natural gas expense.
[2]	The derivative assets and liabilities on the Condensed Consolidated Balance Sheets exclude accounts receivable or accounts payable that, should they exist, could be used as offsets to these balances in the event of a default.
[3]	Gross amounts recognized include some derivative assets and liabilities that are not subject to master netting arrangements.
[4]	Derivative Assets and Derivative Liabilities include no material amounts related to physical forward transactions with Enable.
[5]	Natural gas contracts are presented on a net basis in the Condensed Consolidated Balance Sheets as they are subject to master netting arrangements. This netting applies to all undisputed amounts due or past due and causes derivative assets (liabilities) to be ultimately presented net in a liability (asset) account within the Condensed Consolidated Balance Sheets. The net of total non-trading natural gas derivative assets and liabilities was a $82 million asset and a $130 million asset as of June 30, 2018 and December 31, 2017, respectively, as shown on CenterPoint Energy’s and CERC’s Condensed Consolidated Balance Sheets (and as detailed in the table below), and was comprised of the natural gas contracts derivative assets and liabilities separately shown above, impacted by collateral netting of $32 million and $19 million, respectively.
[6]	The fair value shown for natural gas contracts is comprised of derivative gross volumes totaling 1,862 Bcf or a net 268 Bcf long position and 1,795 Bcf or a net 224 Bcf long position as of June 30, 2018 and December 31, 2017, respectively. Certain natural gas contracts hedge basis risk only and lack a fixed price exposure.

Fair Value Measurements (Detail

Fair Value Measurements (Details)		3 Months Ended		6 Months Ended
		Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair value amount of Level 1 to Level 2 assets transferred		$ 0		$ 0
Fair value amount of Level 2 to Level 1 assets transferred		0		0
Fair value amount of Level 1 to Level 2 liabilities transferred		0		0
Fair value amount of Level 2 to Level 1 liabilities transferred		0		0
Assets
Total derivative assets, netting adjustment	[1]	(40,000,000)		(40,000,000)		$ (64,000,000)
Total assets		776,000,000		776,000,000		1,199,000,000
Liabilities
Total derivative liabilities, netting adjustment	[1]	(72,000,000)		(72,000,000)		(83,000,000)
Total liabilities		680,000,000		680,000,000		692,000,000
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		(662,000,000)	$ (700,000,000)	(622,000,000)	$ (704,000,000)
Total gains (losses)		(11,000,000)	(6,000,000)	(16,000,000)	0
Total settlements		44,000,000	0	11,000,000	(4,000,000)
Transfers into Level 3		1,000,000	1,000,000	1,000,000	2,000,000
Transfers out of Level 3		0	(7,000,000)	(2,000,000)	(6,000,000)
Ending balance (1)	[2]	(628,000,000)	(712,000,000)	(628,000,000)	(712,000,000)
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date:		(9,000,000)	(9,000,000)	(23,000,000)	(2,000,000)
Carrying Amount [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[3]	8,256,000,000		8,256,000,000		8,679,000,000
Fair Value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[3]	8,470,000,000		8,470,000,000		9,220,000,000
Natural gas derivatives [Member]
Assets
Derivative fair value offsets, net		32,000,000		32,000,000		19,000,000
Fair Value, Inputs, Level 1 [Member]
Assets
Total assets		656,000,000		656,000,000		1,045,000,000
Liabilities
Total liabilities		1,000,000		1,000,000		0
Fair Value, Inputs, Level 2 [Member]
Assets
Total assets		142,000,000		142,000,000		161,000,000
Liabilities
Total liabilities		105,000,000		105,000,000		96,000,000
Fair Value, Inputs, Level 3 [Member]
Assets
Total assets		18,000,000		18,000,000		57,000,000
Liabilities
Total liabilities		646,000,000		$ 646,000,000		679,000,000
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair value inputs (price per MMBtu)				1.04
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Fair value inputs (price per MMBtu)				3.31
Fair Value, Measurements, Recurring [Member]
Assets
Corporate equities		586,000,000		$ 586,000,000		963,000,000
Investments, including money market funds (2)	[4]	70,000,000		70,000,000		68,000,000
Hedged portion of natural gas inventory		0		0		14,000,000
Liabilities
Hedged portion of natural gas inventory		1,000,000		1,000,000		0
Fair Value, Measurements, Recurring [Member] | IDS Derivative [Member]
Liabilities
Derivative liabilities, netting adjustment	[1]	0		0		0
Derivative liabilities		641,000,000		641,000,000		668,000,000
Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member]
Assets
Derivative asset, netting adjustment	[1],[5]	(40,000,000)		(40,000,000)		(64,000,000)
Derivative assets	[5]	120,000,000		120,000,000		154,000,000
Liabilities
Derivative liabilities, netting adjustment	[1],[5]	(72,000,000)		(72,000,000)		(83,000,000)
Derivative liabilities	[5]	38,000,000		38,000,000		24,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Corporate equities		586,000,000		586,000,000		963,000,000
Investments, including money market funds (2)	[4]	70,000,000		70,000,000		68,000,000
Hedged portion of natural gas inventory		0		0		14,000,000
Liabilities
Hedged portion of natural gas inventory		1,000,000		1,000,000		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | IDS Derivative [Member]
Liabilities
Derivative liability		0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Natural gas derivatives [Member]
Assets
Derivative asset	[5]	0		0		0
Liabilities
Derivative liability	[5]	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Corporate equities		0		0		0
Investments, including money market funds (2)	[4]	0		0		0
Hedged portion of natural gas inventory		0		0		0
Liabilities
Hedged portion of natural gas inventory		0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | IDS Derivative [Member]
Liabilities
Derivative liability		0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Natural gas derivatives [Member]
Assets
Derivative asset	[5]	142,000,000		142,000,000		161,000,000
Liabilities
Derivative liability	[5]	105,000,000		105,000,000		96,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Corporate equities		0		0		0
Investments, including money market funds (2)	[4]	0		0		0
Hedged portion of natural gas inventory		0		0		0
Liabilities
Hedged portion of natural gas inventory		0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | IDS Derivative [Member]
Liabilities
Derivative liability		641,000,000		641,000,000		668,000,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Natural gas derivatives [Member]
Assets
Derivative asset	[5]	18,000,000		18,000,000		57,000,000
Liabilities
Derivative liability	[5]	5,000,000		5,000,000		11,000,000
CERC Corp [Member]
Assets
Total derivative assets, netting adjustment	[1]	(40,000,000)		(40,000,000)		(64,000,000)
Total assets		133,000,000		133,000,000		182,000,000
Liabilities
Total derivative liabilities, netting adjustment	[1]	(72,000,000)		(72,000,000)		(83,000,000)
Total liabilities		39,000,000		39,000,000		24,000,000
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		12,000,000	27,000,000	46,000,000	13,000,000
Total gains (losses)		1,000,000	7,000,000	3,000,000	23,000,000
Total settlements		(1,000,000)	0	(35,000,000)	(4,000,000)
Transfers into Level 3		1,000,000	1,000,000	1,000,000	2,000,000
Transfers out of Level 3		0	(7,000,000)	(2,000,000)	(6,000,000)
Ending balance (1)	[2]	13,000,000	28,000,000	13,000,000	28,000,000
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at the reporting date:		3,000,000	$ 4,000,000	(4,000,000)	$ 21,000,000
CERC Corp [Member] | Carrying Amount [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities		2,722,000,000		2,722,000,000		2,457,000,000
CERC Corp [Member] | Fair Value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities		2,876,000,000		2,876,000,000		2,708,000,000
CERC Corp [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Total assets		13,000,000		13,000,000		28,000,000
Liabilities
Total liabilities		1,000,000		1,000,000		0
CERC Corp [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Total assets		142,000,000		142,000,000		161,000,000
Liabilities
Total liabilities		105,000,000		105,000,000		96,000,000
CERC Corp [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Total assets		18,000,000		18,000,000		57,000,000
Liabilities
Total liabilities		5,000,000		5,000,000		11,000,000
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Corporate equities		2,000,000		2,000,000		3,000,000
Investments, including money market funds (2)	[4]	11,000,000		11,000,000		11,000,000
Hedged portion of natural gas inventory		0		0		14,000,000
Liabilities
Hedged portion of natural gas inventory		1,000,000		1,000,000		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Natural gas derivatives [Member]
Assets
Derivative asset, netting adjustment	[1],[5]	(40,000,000)		(40,000,000)		(64,000,000)
Derivative assets	[5]	120,000,000		120,000,000		154,000,000
Liabilities
Derivative liabilities, netting adjustment	[1],[5]	(72,000,000)		(72,000,000)		(83,000,000)
Derivative liabilities	[5]	38,000,000		38,000,000		24,000,000
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Corporate equities		2,000,000		2,000,000		3,000,000
Investments, including money market funds (2)	[4]	11,000,000		11,000,000		11,000,000
Hedged portion of natural gas inventory		0		0		14,000,000
Liabilities
Hedged portion of natural gas inventory		1,000,000		1,000,000		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Natural gas derivatives [Member]
Assets
Derivative asset	[5]	0		0		0
Liabilities
Derivative liability	[5]	0		0		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Corporate equities		0		0		0
Investments, including money market funds (2)	[4]	0		0		0
Hedged portion of natural gas inventory		0		0		0
Liabilities
Hedged portion of natural gas inventory		0		0		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Natural gas derivatives [Member]
Assets
Derivative asset	[5]	142,000,000		142,000,000		161,000,000
Liabilities
Derivative liability	[5]	105,000,000		105,000,000		96,000,000
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Corporate equities		0		0		0
Investments, including money market funds (2)	[4]	0		0		0
Hedged portion of natural gas inventory		0		0		0
Liabilities
Hedged portion of natural gas inventory		0		0		0
CERC Corp [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Natural gas derivatives [Member]
Assets
Derivative asset	[5]	18,000,000		18,000,000		57,000,000
Liabilities
Derivative liability	[5]	5,000,000		5,000,000		11,000,000
Houston Electric [Member]
Assets
Total derivative assets, netting adjustment		0		0		0
Total assets		52,000,000		52,000,000		51,000,000
Houston Electric [Member] | Carrying Amount [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[3]	4,919,000,000		4,919,000,000		4,753,000,000
Houston Electric [Member] | Fair Value [Member]
Estimated Fair Value of Financial Instruments
Long-term debt, including current maturities	[3]	4,991,000,000		4,991,000,000		5,034,000,000
Houston Electric [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Total assets		52,000,000		52,000,000		51,000,000
Houston Electric [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Total assets		0		0		0
Houston Electric [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Total assets		0		0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Investments, including money market funds (2)	[4]	52,000,000		52,000,000		51,000,000
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets
Investments, including money market funds (2)	[4]	52,000,000		52,000,000		51,000,000
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets
Investments, including money market funds (2)	[4]	0		0		0
Houston Electric [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets
Investments, including money market funds (2)	[4]	$ 0		$ 0		$ 0
[1]	Amounts represent the impact of legally enforceable master netting arrangements that allow CenterPoint Energy and CERC to settle positive and negative positions and also include cash collateral of $32 million and $19 million as of June 30, 2018 and December 31, 2017, respectively, posted with the same counterparties.
[2]	CenterPoint Energy and CERC did not have significant Level 3 sales or purchases during either of the three or six months ended June 30, 2018 or 2017.
[3]	Includes Securitization Bond debt.
[4]	Amounts are included in Prepaid expenses and other current assets in the Condensed Consolidated Balance Sheets.
[5]	Natural gas derivatives include no material amounts related to physical forward transactions with Enable.

Unconsolidated Affiliate (Cen52

Unconsolidated Affiliate (CenterPoint Energy and CERC) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Enable Units [Abstract]
Preferred units – unconsolidated affiliate		$ 363		$ 363		$ 363
Percentage of sales that trigger right of first refusal				5.00%
Enable Distributions [Abstract]
Total distributions received from Enable		84	$ 84	$ 167	$ 167
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
CenterPoint Energy’s and CERC’s equity in earnings, net		58	59	127	131
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s and CERC’s equity method investment in Enable		2,451		2,451		2,472
CERC Corp [Member]
Enable Distributions [Abstract]
Total distributions received from Enable		75	75	149	149
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
CenterPoint Energy’s and CERC’s equity in earnings, net		58	59	127	131
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s and CERC’s equity method investment in Enable		$ 2,451		$ 2,451		2,472
OGE [Member]
Enable Units [Abstract]
Percentage of sales that trigger right of first refusal				5.00%
Enable Midstream Partners [Member]
Enable Partnership Interest [Abstract]
Ownership percentage of equity method investment		54.00%		54.00%
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss) [Abstract]
Operating revenues		$ 805	626	$ 1,553	1,292
Cost of sales, excluding depreciation and amortization		444	279	819	587
Operating income		126	122	265	262
Net income attributable to Enable		86	86	191	197
CenterPoint Energy’s and CERC’s interest		46	47	103	107
Basis difference amortization (1)	[1]	12	12	24	24
CenterPoint Energy’s and CERC’s equity in earnings, net		58	59	$ 127	131
Basis difference amortization period				31 years
Equity Method Investment, Summarized Financial Information, Assets and Liabilities [Abstract]
Current assets		432		$ 432		416
Non-current assets		11,360		11,360		11,177
Current liabilities		1,258		1,258		1,279
Non-current liabilities		2,963		2,963		2,660
Non-controlling interest		11		11		12
Preferred equity		362		362		362
Enable partners’ equity		7,198		7,198		7,280
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
CenterPoint Energy’s and CERC’s ownership interest in Enable partners’ equity		3,887		3,887		3,935
CenterPoint Energy’s and CERC’s basis difference		(1,436)		(1,436)		(1,463)
CenterPoint Energy’s and CERC’s equity method investment in Enable		2,451		2,451		2,472
Enable Midstream Partners [Member] | Common Units [Member]
Enable Distributions [Abstract]
Distributions received from Enable equity method investment		75	75	149	149
Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Enable Distributions [Abstract]
Distributions received from Enable cost method investment		$ 9	9	$ 18	18
Enable Midstream Partners [Member] | CERC Corp [Member]
Enable Partnership Interest [Abstract]
Ownership percentage of equity method investment	[2]	54.00%		54.00%
Enable Midstream Partners [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[2]			100.00%
Enable Distributions [Abstract]
Maximum incentive distribution right				50.00%
Enable Midstream Partners [Member] | CERC Corp [Member]
Enable Units [Abstract]
Management rights ownership percentage				50.00%
Enable Distributions [Abstract]
Incentive distribution right				40.00%
Enable Midstream Partners [Member] | OGE [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[2]			25.60%
Enable Units [Abstract]
Management rights ownership percentage				50.00%
Enable Distributions [Abstract]
Incentive distribution right				60.00%
Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Partnership Interest [Abstract]
Limited partner ownership interest	[2]			20.40%
Enable Midstream Partners [Member] | Minimum [Member]
Enable Distributions [Abstract]
Incentive distribution per unit				$ 0.2875
Enable Midstream Partners [Member] | Maximum [Member]
Enable Distributions [Abstract]
Incentive distribution per unit				$ 0.330625
Common Units [Member] | Enable Midstream Partners [Member] | CERC Corp [Member]
Enable Units [Abstract]
Limited partner interest units held		233,856,623		233,856,623
Common Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Limited partner interest units held		433,064,636		433,064,636
Common Units [Member] | Enable Midstream Partners [Member] | OGE [Member]
Enable Units [Abstract]
Limited partner interest units held		110,982,805		110,982,805
Common Units [Member] | Enable Midstream Partners [Member] | Public unitholders [Member]
Enable Units [Abstract]
Limited partner interest units held		88,225,208		88,225,208
Series A Preferred Units [Member] | Enable Midstream Partners [Member]
Enable Units [Abstract]
Preferred Units Held	[3]	14,520,000		14,520,000
Transitional Service [Member] | Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Reimbursement of transition services (1)	[4]	$ 1	1	$ 3	3
Accounts receivable for amounts billed for transition services		3		3		1
Natural Gas Expenses [Member] | Enable Midstream Partners [Member]
Transactions with Enable [Abstract]
Natural gas expenses, including transportation and storage costs		29	$ 24	66	$ 57
Accounts payable for natural gas purchases from Enable		$ 8		$ 8		$ 13
[1]	Equity in earnings of unconsolidated affiliate includes CenterPoint Energy’s and CERC’s share of Enable’s earnings adjusted for the amortization of the basis difference of CenterPoint Energy’s and CERC’s original investment in Enable and their underlying equity in Enable’s net assets. The basis difference is amortized over approximately 31 years, the average life of the assets to which the basis difference is attributed.
[2]	Excluding the Series A Preferred Units owned by CenterPoint Energy.
[3]	The carrying amount of the Series A Preferred Units, reflected as Preferred units - unconsolidated affiliate on CenterPoint Energy’s Condensed Consolidated Balance Sheets, was $363 million as of both June 30, 2018 and December 31, 2017. No impairment charges or adjustment due to observable price changes were made during the current or prior reporting periods. See Note 2 for further discussion.
[4]	Represents amounts billed under the Transition Agreements for certain support services provided to Enable. Actual transition services costs are recorded net of reimbursement.

Goodwill and Other Intangible53

Goodwill and Other Intangibles (CenterPoint Energy and CERC) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Goodwill [Line Items]
Goodwill		$ 867		$ 867		$ 867
Intangible assets gross carrying amount		105		105		105
Intangible assets accumulated amortization		(36)		(36)		(31)
Net intangible assets		69		69		74
Amortization expense of intangible assets		2	$ 1	5	$ 3
Natural Gas Distribution [Member]
Goodwill [Line Items]
Goodwill		746		746		746
Energy Services [Member]
Goodwill [Line Items]
Goodwill	[1]	110		110		110
Accumulated goodwill impairment charge recorded in 2012		252		252		252
Other Operations [Member]
Goodwill [Line Items]
Goodwill		11		$ 11		$ 11
Customer Relationships [Member]
Goodwill [Line Items]
Intangible asset useful lives				15 years		15 years
Intangible assets gross carrying amount		86		$ 86		$ 86
Intangible assets accumulated amortization		(25)		(25)		(21)
Net intangible assets		61		$ 61		$ 65
Noncompete Agreements [Member]
Goodwill [Line Items]
Intangible asset useful lives				4 years		4 years
Intangible assets gross carrying amount		4		$ 4		$ 4
Intangible assets accumulated amortization		(2)		(2)		(2)
Net intangible assets		2		2		2
Other Intangible Assets [Member]
Goodwill [Line Items]
Intangible assets gross carrying amount		15		15		15
Intangible assets accumulated amortization		(9)		(9)		(8)
Net intangible assets		$ 6		$ 6		$ 7
[1]	Amount presented is net of the accumulated goodwill impairment charge of $252 million recorded in 2012.

Indexed Debt Securities (ZENS54

Indexed Debt Securities (ZENS) and Securities Related to ZENS (CenterPoint Energy) (Details) $ / shares in Units, $ in Millions		Jul. 17, 2018USD ($)	Jun. 30, 2018USD ($)shares$ / shares	Jun. 30, 2017USD ($)	Jun. 14, 2018$ / sharesshares	Jan. 31, 2018$ / shares	Dec. 31, 2017USD ($)shares	Nov. 26, 2017$ / shares
Cash paid per share exchanged | $ / shares			$ 72
Distribution To ZENS holders			$ 16	$ 0
Due to ZENS note holders			382				$ 0
Subordinated Debt ZENS [Member]
Principal amount of debt issued			1,000
Outstanding debt balance			$ 828
Subordinated note cash exchangeable percentage of fair value			95.00%
Contingent principal amount outstanding			$ 484
AT&T Common [Member]
Balance of investment owned (in shares) | shares			10,212,945
AT&T Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares			0.7185
Charter Common [Member]
Balance of investment owned (in shares) | shares			872,503				872,503
Charter Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares			0.061382				0.061382
Time Common [Member]
Balance of investment owned (in shares) | shares							888,392
ZENS early exchange ratio						100.00%
Time Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares							0.0625
TW Common [Member]
Balance of investment owned (in shares) | shares							7,107,130
TW Common [Member] | Subordinated Debt ZENS [Member]
Number of shares referenced in exchangeable subordinated note | shares							0.5
AT&T To Acquire Time Warner [Member]
Due to ZENS note holders	[1]		$ 382
Indexed debt – reduction			(95)
Indexed debt securities derivative – reduction			(45)
Loss on indexed debt securities			242
AT&T To Acquire Time Warner [Member] | AT&T Common [Member]
Cash paid per share exchanged | $ / shares					$ 53.75
Fractional shares exchanged for each TW Common share held | shares					1.437
Cash proceeds received for shares exchanged			382
Total AT&T shares received in exchange for TW Common shares held | shares					10,212,945
Meredith to acquire Time [Member]
Distribution To ZENS holders			16
Indexed debt – reduction			(4)
Indexed debt securities derivative – reduction			(1)
Loss on indexed debt securities			11
Meredith to acquire Time [Member] | Time Common [Member]
Cash paid per share exchanged | $ / shares						$ 18.50		$ 18.50
Cash proceeds received for shares exchanged			$ 16
Subsequent Event [Member]
Distribution To ZENS holders		$ 382
[1]	Cash of approximately $382 million was paid to ZENS note holders in July 2018.

Short-Term Borrowings and Lon55

Short-Term Borrowings and Long-term Debt (Details)		Mar. 26, 2018USD ($)	Feb. 28, 2018USD ($)	Jun. 30, 2018USD ($)		Dec. 31, 2017USD ($)
Short-term Debt [Line Items]
Short-term borrowings				$ 0		$ 39,000,000
Line of Credit Facility [Abstract]
Size of credit facility				2,900,000,000		2,900,000,000
Parent Company [Member]
Line of Credit Facility [Abstract]
Size of credit facility				1,700,000,000	[1]	1,700,000,000
Temporary increased line of credit facility, maximum borrowing capacity				3,300,000,000
Houston Electric [Member]
Line of Credit Facility [Abstract]
Size of credit facility				300,000,000		300,000,000
General mortgage bonds used as collateral				118,000,000		118,000,000
CERC Corp [Member]
Short-term Debt [Line Items]
Short-term borrowings				0		39,000,000
Line of Credit Facility [Abstract]
Size of credit facility				900,000,000		900,000,000
Revolving Credit Facility [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				0		0
Revolving Credit Facility [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[2]			0		0
Revolving Credit Facility [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				0		0
Revolving Credit Facility [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 0		0
Line of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant				65.00%
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)				70.00%
Ratio of indebtedness to net capital	[3]			0.521
System restoration costs threshold for increase in permitted debt to EBITDA covenant ratio				$ 100,000,000
Consecutive period for system restoration costs to exceed $100 million (in months)				12
Line of Credit [Member] | Parent Company [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[4]			1.25%
Line of Credit [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant	[5]			65.00%
Ratio of indebtedness to net capital	[3]			0.507
Line of Credit [Member] | Houston Electric [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[4]			1.125%
Line of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant				65.00%
Ratio of indebtedness to net capital	[3]			0.378
Line of Credit [Member] | CERC Corp [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Abstract]
Basis spread on LIBOR	[4]			1.25%
Letter of Credit [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 11,000,000		11,000,000
Letter of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[2]			6,000,000		6,000,000
Letter of Credit [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				4,000,000		4,000,000
Letter of Credit [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				1,000,000		1,000,000
Commercial Paper [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				565,000,000		1,753,000,000
Commercial Paper [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Long-term line of credit	[2]			$ 0		$ 855,000,000
Weighted average interest rate of debt	[2]			0.00%		1.88%
Commercial Paper [Member] | Houston Electric [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 0		$ 0
Commercial Paper [Member] | CERC Corp [Member]
Line of Credit Facility [Abstract]
Long-term line of credit				$ 565,000,000		$ 898,000,000
Weighted average interest rate of debt				2.37%		1.72%
General Mortgage Bonds Due 2048 [Member] | Houston Electric [Member]
Debt Instruments [Abstract]
Principal amount of debt issued			$ 400,000,000
Interest rate of debt issued			3.95%
Maturity date of debt issued			Mar. 1, 2048
Senior Notes Due 2023 [Member] | CERC Corp [Member]
Debt Instruments [Abstract]
Principal amount of debt issued		$ 300,000,000
Interest rate of debt issued		3.55%
Maturity date of debt issued		Apr. 1, 2023
Senior Notes Due 2028 [Member]
Debt Instruments [Abstract]
Principal amount of debt issued		$ 300,000,000
Interest rate of debt issued		4.00%
Maturity date of debt issued		Apr. 1, 2028
Product Financing Arrangement [Member]
Short-term Debt [Line Items]
Short-term borrowings				$ 0		$ 39,000,000
Merger Agreement with Vectren [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Temporary increased line of credit facility, maximum borrowing capacity				$ 3,300,000,000
Merger Agreement with Vectren [Member] | Line of Credit [Member] | Parent Company [Member]
Line of Credit Facility [Abstract]
Percentage on limitation of debt to total capitalization under covenant amended (in hundredths)	[5],[6]			75.00%
[1]	Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility will increase to $3.3 billion upon the satisfaction of certain conditions described above.
[2]	Pursuant to the amendment entered into in May 2018, the aggregate commitments under the CenterPoint Energy revolving credit facility will increase to $3.3 billion upon the satisfaction of certain conditions described above.
[3]	As defined in the revolving credit facility agreement, excluding Securitization Bonds.
[4]	Based on current credit ratings.
[5]	For CenterPoint Energy (whenever its financial covenant limit is 65%) and Houston Electric, the financial covenant limit will temporarily increase from 65% to 70% if Houston Electric experiences damage from a natural disaster in its service territory and CenterPoint Energy certifies to the administrative agent that Houston Electric has incurred system restoration costs reasonably likely to exceed $100 million in a consecutive 12-month period, all or part of which Houston Electric intends to seek to recover through securitization financing. Such temporary increase in the financial covenant would be in effect from the date CenterPoint Energy delivers its certification until the earliest to occur of (i) the completion of the securitization financing, (ii) the first anniversary of CenterPoint Energy’s certification or (iii) the revocation of such certification.
[6]	CenterPoint Energy’s financial covenant limit will return to 65% upon the earlier of (i) June 30, 2019 or (ii) the termination of all commitments in respect of the Bridge Facility without any borrowing thereunder.

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Effective income tax rate	15.00%	36.00%	27.00%	36.00%
Federal statutory income tax rate			21.00%	35.00%
Houston Electric [Member]
Effective income tax rate	21.00%	36.00%	22.00%	36.00%
CERC Corp [Member]
Effective income tax rate	22.00%	35.00%	22.00%	37.00%

Commitments and Contingencies57

Commitments and Contingencies (Details)	6 Months Ended
	Jun. 30, 2018USD ($)
CERC Corp [Member] | Minnesota Service Territory [Member]
Legal, Environmental and Other Matters
Liability recorded for remediation of Minnesota sites	$ 7,000,000
CERC Corp [Member] | Minnesota Service Territory [Member] | Minimum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 4,000,000
Years to resolve contingency	30 years
CERC Corp [Member] | Minnesota Service Territory [Member] | Maximum [Member]
Legal, Environmental and Other Matters
Estimated remediation costs for the Minnesota sites	$ 30,000,000
Years to resolve contingency	50 years
Natural Gas Supply Commitments [Member]
Natural Gas Supply Commitments
Remaining six months of 2018	$ 185,000,000
2,019	264,000,000
2,020	168,000,000
2,021	82,000,000
2,022	51,000,000
2023 and beyond	123,000,000
Minnehaha Academy Gas Explosion [Member]
Legal, Environmental and Other Matters
Contested amount of fines imposed	$ 200,000

Earnings Per Share (CenterPoi58

Earnings Per Share (CenterPoint Energy) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net income (loss)	$ (75)		$ 135	$ 90	$ 327
Basic weighted average shares outstanding	431,523,000		430,996,000	431,378,000	430,896,000
Plus: Incremental shares from assumed conversions:
Diluted weighted average shares	431,523,000		433,797,000	434,407,000	433,697,000
Basic earnings (loss) per share
Net income (loss)	$ (0.17)		$ 0.31	$ 0.21	$ 0.76
Diluted earnings (loss) per share
Net income (loss)	$ (0.17)		$ 0.31	$ 0.21	$ 0.75
Restricted Stock [Member]
Anti-dilutive shares excluded from computation of diluted earnings (loss) per share	3,029,000
Plus: Incremental shares from assumed conversions:
Restricted stock (1)	0	[1]	2,801,000	3,029,000	2,801,000
[1]	3,029,000 incremental shares from assumed conversions of restricted stock have not been included in the computation of diluted earnings (loss) per share for the three months ended June 30, 2018 as their inclusion would be anti-dilutive.

Reportable Business Segments (D

Reportable Business Segments (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues		$ 2,186	$ 2,143	$ 5,341	$ 4,878
Operating Income (Loss)		187	240	438	531
Equity in earnings from investment in Enable		58	59	127	131
Assets		22,108		22,108		$ 22,736
Total regulatory assets		2,122		2,122		2,477
Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	854	752	1,605	1,391
Operating Income (Loss)		181	171	296	257
Electric Transmission and Distribution [Member] | Affiliates of NRG Energy, Inc. [Member]
Segment Reporting Information [Line Items]
Revenues		169	167	330	319
Electric Transmission and Distribution [Member] | Affiliates of Vistra Energy Corp. [Member]
Segment Reporting Information [Line Items]
Revenues		59	53	113	100
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		487	470	1,630	1,377
Operating Income (Loss)		7	42	163	210
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		841	918	2,098	2,103
Operating Income (Loss)		15	16	(11)	51
Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0	0	0	0
Operating Income (Loss)	[2]	0	0	0	0
Equity in earnings from investment in Enable		58	59	127	131
Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		4	3	8	7
Operating Income (Loss)		(16)	11	(10)	13
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(27)	(20)	(65)	(40)
Assets		(841)		(841)		(654)
Intersegment Eliminations [Member] | Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		(8)	(7)	(18)	(16)
Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(19)	(13)	(47)	(24)
Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0	0	0	0
Intersegment Eliminations [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		0	0	0	0
Operating Segments [Member] | Electric Transmission and Distribution [Member]
Segment Reporting Information [Line Items]
Assets		10,430		10,430		10,292
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		6,501		6,501		6,608
Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		1,256		1,256		1,521
Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets		2,451		2,451		2,472
Operating Segments [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Assets	[3]	2,311		2,311		2,497
Pension and Other Postretirement Plans Costs [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Total regulatory assets		577		577		600
CERC Corp [Member]
Segment Reporting Information [Line Items]
Revenues		1,328	1,387	3,728	3,480
Operating Income (Loss)		22	59	153	258
Equity in earnings from investment in Enable		58	59	127	131
Assets		9,642		9,642		10,112
Total regulatory assets		228		228		311
CERC Corp [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		487	470	1,630	1,377
Operating Income (Loss)		7	42	163	210
CERC Corp [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		841	918	2,098	2,103
Operating Income (Loss)		15	16	(11)	51
CERC Corp [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0	0	0	0
Operating Income (Loss)	[2]	0	0	0	0
CERC Corp [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		0	(1)	0	0
Operating Income (Loss)		0	1	1	(3)
CERC Corp [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(27)	(20)	(65)	(40)
Assets		(655)		(655)		(559)
CERC Corp [Member] | Intersegment Eliminations [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Revenues		(8)	(7)	(18)	(16)
CERC Corp [Member] | Intersegment Eliminations [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Revenues		(19)	(13)	(47)	(24)
CERC Corp [Member] | Intersegment Eliminations [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Revenues	[2]	0	0	0	0
CERC Corp [Member] | Intersegment Eliminations [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Revenues		0	$ 0	0	$ 0
CERC Corp [Member] | Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets		6,501		6,501		6,608
CERC Corp [Member] | Operating Segments [Member] | Energy Services [Member]
Segment Reporting Information [Line Items]
Assets		1,256		1,256		1,521
CERC Corp [Member] | Operating Segments [Member] | Midstream Investments [Member]
Segment Reporting Information [Line Items]
Assets		2,451		2,451		2,472
CERC Corp [Member] | Operating Segments [Member] | Other Operations [Member]
Segment Reporting Information [Line Items]
Assets		$ 89		$ 89		$ 70
[1]	CenterPoint Energy’s and Houston Electric’s Electric Transmission & Distribution revenues from major customers are as follows:
[2]	CenterPoint Energy’s and CERC’s Midstream Investments’ equity earnings, net are as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (in millions)Enable $58 $59 $127 $131
[3]	Includes pension and other postemployment-related regulatory assets of $577 million and $600 million, respectively, as of June 30, 2018 and December 31, 2017.

Supplemental Disclosure of Ca60

Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Interest, net of capitalized interest	$ 167	$ 182
Income taxes, net	88	11
Accounts payable related to capital expenditures	133	106
Cash and cash equivalents	328		$ 260
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	366	280	296	$ 381
Prepaid expenses and other current assets [Member]
Restricted cash	37		35
Other [Member]
Restricted cash	1		1
Houston Electric [Member]
Interest, net of capitalized interest	90	94
Income taxes, net	120	76
Accounts payable related to capital expenditures	75	75
Cash and cash equivalents	253		238
Total cash, cash equivalents and restricted cash shown in Condensed Statements of Consolidated Cash Flows	291	277	274	381
Houston Electric [Member] | Prepaid expenses and other current assets [Member]
Restricted cash	37		35
Houston Electric [Member] | Other [Member]
Restricted cash	1		1
CERC Corp [Member]
Interest, net of capitalized interest	50	56
Income taxes, net	3	3
Accounts payable related to capital expenditures	69	44
Cash and cash equivalents	$ 1	$ 1	$ 12	$ 1

Related Party Transactions (H61

Related Party Transactions (Houston Electric and CERC) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Houston Electric [Member]
Related Party Transaction [Line Items]
Dividends paid		$ 31	$ 10	$ 63	$ 42
Houston Electric [Member] | Operation and maintenance expense [Member]
Related Party Transaction [Line Items]
Net affiliate service charges (billings)		(3)	(4)	(5)	(5)
Houston Electric [Member] | CenterPoint Energy [Member] | Operation and maintenance expense [Member]
Related Party Transaction [Line Items]
Corporate service charges		47	44	91	86
CERC Corp [Member]
Related Party Transaction [Line Items]
Dividends paid		125	140	211	248
CERC Corp [Member] | Operation and maintenance expense [Member]
Related Party Transaction [Line Items]
Net affiliate service charges (billings)		3	4	5	5
CERC Corp [Member] | CenterPoint Energy [Member] | Operation and maintenance expense [Member]
Related Party Transaction [Line Items]
Corporate service charges		$ 35	$ 32	$ 69	$ 63
Investments [Member] | Houston Electric [Member]
Related Party Transaction [Line Items]
Weighted average interest rate		2.00%		2.00%		1.90%
Investments [Member] | CERC Corp [Member]
Related Party Transaction [Line Items]
Weighted average interest rate		0.00%		0.00%		1.90%
Accounts and notes receivable (payable) - affiliate companies [Member] | Houston Electric [Member]
Related Party Transaction [Line Items]
Money pool investments (borrowings) (1)	[1]	$ 26		$ 26		$ (60)
Accounts and notes receivable (payable) - affiliate companies [Member] | CERC Corp [Member]
Related Party Transaction [Line Items]
Money pool investments (borrowings) (1)	[1]	$ 0		$ 0		$ (570)
[1]	Included in Accounts and notes receivable (payable)–affiliated companies in the Condensed Consolidated Balance Sheets.

Subsequent Events (CenterPoin62

Subsequent Events (CenterPoint Energy and CERC) (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 01, 2018	Jul. 26, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Subsequent Event [Line Items]
Quarterly cash dividend/distribution declared per share			$ 0.2775	$ 0.2675	$ 0.2775	$ 0.5350
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends payable, date declared		Jul. 26, 2018
Quarterly cash dividend/distribution declared per share		$ 0.2775
Dividends payable, date to be paid		Sep. 13, 2018
Dividends payable, date of record		Aug. 16, 2018
Subsequent Event [Member] | Enable Midstream Partners [Member] | Common Units [Member]
Subsequent Event [Line Items]
Dividends payable, date declared	Aug. 1, 2018
Quarterly cash dividend/distribution declared per share	$ 0.318
Expected cash distribution from equity method investment	$ 74
Subsequent Event [Member] | Enable Midstream Partners [Member] | Series A Preferred Units [Member]
Subsequent Event [Line Items]
Dividends payable, date declared	Aug. 1, 2018
Preferred stock dividends declared per share	$ 0.625
Expected cash distribution from cost method investment	$ 9